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Kotlin-based LeetCode algorithm problem solutions, regularly updated.

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LeetCode-in-Kotlin

Maven Central MIT License Java CI with Maven Maintainability Rating javadoc

Kotlin-based LeetCode algorithm problem solutions, regularly updated.

Installation

To configure your Maven project, add the following code to your pom.xml file:

<dependencies>
  <dependency>
    <groupId>com.github.javadev</groupId>
    <artifactId>leetcode-in-kotlin</artifactId>
    <version>1.32</version>
  </dependency>
  ...
</dependencies>

Gradle configuration:

implementation 'com.github.javadev:leetcode-in-kotlin:1.32'

"For coding interview preparation, LeetCode is one of the best online resource providing a rich library of more than 300 real coding interview questions for you to practice from using one of the 7 supported languages - C, C++, Java, Python, C#, JavaScript, Ruby."

Algorithm I

Day 1 Binary Search
0704 Binary Search Easy Top_100_Liked_Questions, Array, Binary_Search 261 77.91
0278 First Bad Version Easy Binary_Search, Interactive 349 76.86
0035 Search Insert Position Easy Top_100_Liked_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 159 93.03

Day 2 Two Pointers
0977 Squares of a Sorted Array Easy Array, Sorting, Two_Pointers 271 77.17
0189 Rotate Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Math, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 483 86.95

Day 3 Two Pointers
0283 Move Zeroes Easy Top_100_Liked_Questions, Array, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 516 79.07
0167 Two Sum II - Input Array Is Sorted Medium Array, Binary_Search, Two_Pointers 403 68.74

Day 4 Two Pointers
0344 Reverse String Easy String, Two_Pointers, Recursion 445 69.75
0557 Reverse Words in a String III Easy String, Two_Pointers 215 98.10

Day 5 Two Pointers
0876 Middle of the Linked List Easy Two_Pointers, Linked_List 136 76.52
0019 Remove Nth Node From End of List Medium Top_100_Liked_Questions, Top_Interview_Questions, Two_Pointers, Linked_List, Big_O_Time_O(L)_Space_O(L) 144 96.28

Day 6 Sliding Window
0003 Longest Substring Without Repeating Characters Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n)_Space_O(1), AI_can_be_used_to_solve_the_task 201 87.28
0567 Permutation in String Medium Top_100_Liked_Questions, String, Hash_Table, Two_Pointers, Sliding_Window 169 100.00

Day 7 Breadth First Search Depth First Search
0733 Flood Fill Easy Array, Depth_First_Search, Breadth_First_Search, Matrix 230 97.76
0695 Max Area of Island Medium Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find 181 93.83

Day 8 Breadth First Search Depth First Search
0617 Merge Two Binary Trees Easy Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 243 72.83
0116 Populating Next Right Pointers in Each Node Medium Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Linked_List 355 69.02

Day 9 Breadth First Search Depth First Search
0542 01 Matrix Medium Array, Dynamic_Programming, Breadth_First_Search, Matrix 441 94.06
0994 Rotting Oranges Medium Top_100_Liked_Questions, Array, Breadth_First_Search, Matrix 164 82.95

Day 10 Recursion Backtracking
0021 Merge Two Sorted Lists Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) 157 92.24
0206 Reverse Linked List Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(N)_Space_O(1) 279 45.78

Day 11 Recursion Backtracking
0077 Combinations Medium Backtracking 232 100.00
0046 Permutations Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Backtracking, Big_O_Time_O(n*n!)_Space_O(n+n!) 188 99.00
0784 Letter Case Permutation Medium String, Bit_Manipulation, Backtracking 219 84.62

Day 12 Dynamic Programming
0070 Climbing Stairs Easy Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization, Big_O_Time_O(n)_Space_O(n) 124 71.98
0198 House Robber Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 156 92.24
0120 Triangle Medium Array, Dynamic_Programming 194 97.87

Day 13 Bit Manipulation
0231 Power of Two Easy Math, Bit_Manipulation, Recursion 161 86.81
0191 Number of 1 Bits Easy Top_Interview_Questions, Bit_Manipulation 237 68.44

Day 14 Bit Manipulation
0190 Reverse Bits Easy Top_Interview_Questions, Bit_Manipulation, Divide_and_Conquer 198 81.82
0136 Single Number Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) 344 83.63

Algorithm II

Day 1 Binary Search
0034 Find First and Last Position of Element in Sorted Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 174 100.00
0033 Search in Rotated Sorted Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 151 93.77
0074 Search a 2D Matrix Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Big_O_Time_O(endRow+endCol)_Space_O(1) 159 74.46

Day 2 Binary Search
0153 Find Minimum in Rotated Sorted Array Medium Top_100_Liked_Questions, Array, Binary_Search, Big_O_Time_O(log_N)_Space_O(log_N) 262 60.96
0162 Find Peak Element Medium Top_Interview_Questions, Array, Binary_Search 297 53.85

Day 3 Two Pointers
0082 Remove Duplicates from Sorted List II Medium Two_Pointers, Linked_List 166 89.47
0015 3Sum Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n*log(n))_Space_O(n^2) 493 93.45

Day 4 Two Pointers
0844 Backspace String Compare Easy String, Two_Pointers, Stack, Simulation 126 98.31
0986 Interval List Intersections Medium Array, Two_Pointers 318 60.98
0011 Container With Most Water Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Greedy, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 402 78.57

Day 5 Sliding Window
0438 Find All Anagrams in a String Medium Top_100_Liked_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n+m)_Space_O(1) 561 54.68
0713 Subarray Product Less Than K Medium Array, Sliding_Window 336 92.11
0209 Minimum Size Subarray Sum Medium Array, Binary_Search, Prefix_Sum, Sliding_Window 315 96.73

Day 6 Breadth First Search Depth First Search
0200 Number of Islands Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find, Big_O_Time_O(M*N)_Space_O(M*N) 252 95.41
0547 Number of Provinces Medium Depth_First_Search, Breadth_First_Search, Graph, Union_Find 229 79.73

Day 7 Breadth First Search Depth First Search
0117 Populating Next Right Pointers in Each Node II Medium Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Linked_List 199 94.67
0572 Subtree of Another Tree Easy Depth_First_Search, Tree, Binary_Tree, Hash_Function, String_Matching 214 92.39

Day 8 Breadth First Search Depth First Search
1091 Shortest Path in Binary Matrix Medium Array, Breadth_First_Search, Matrix 305 98.28
0130 Surrounded Regions Medium Top_Interview_Questions, Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find 355 84.42
0797 All Paths From Source to Target Medium Depth_First_Search, Breadth_First_Search, Graph, Backtracking 232 100.00

Day 9 Recursion Backtracking
0078 Subsets Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Backtracking, Big_O_Time_O(2^n)_Space_O(n*2^n) 171 94.92
0090 Subsets II Medium Array, Bit_Manipulation, Backtracking 200 88.33

Day 10 Recursion Backtracking
0047 Permutations II Medium Array, Backtracking 199 100.00
0039 Combination Sum Medium Top_100_Liked_Questions, Array, Backtracking, Big_O_Time_O(2^n)_Space_O(n+2^n) 226 88.89
0040 Combination Sum II Medium Array, Backtracking 217 93.75

Day 11 Recursion Backtracking
0017 Letter Combinations of a Phone Number Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Backtracking, Big_O_Time_O(4^n)_Space_O(n) 155 95.24
0022 Generate Parentheses Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Backtracking, Big_O_Time_O(2^n)_Space_O(n) 161 85.45
0079 Word Search Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Matrix, Backtracking, Big_O_Time_O(4^(m*n))_Space_O(m*n) 392 72.92

Day 12 Dynamic Programming
0213 House Robber II Medium Array, Dynamic_Programming 257 59.62
0055 Jump Game Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Greedy, Big_O_Time_O(n)_Space_O(1) 332 89.35

Day 13 Dynamic Programming
0045 Jump Game II Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Greedy, Big_O_Time_O(n)_Space_O(1) 208 93.37
0062 Unique Paths Medium Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Combinatorics, Big_O_Time_O(m*n)_Space_O(m*n) 118 94.65

Day 14 Dynamic Programming
0005 Longest Palindromic Substring Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 162 99.00
0413 Arithmetic Slices Medium Array, Dynamic_Programming 156 100.00

Day 15 Dynamic Programming
0091 Decode Ways Medium Top_Interview_Questions, String, Dynamic_Programming 148 79.07
0139 Word Break Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Big_O_Time_O(M+max*N)_Space_O(M+N+max) 197 87.17

Day 16 Dynamic Programming
0300 Longest Increasing Subsequence Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Binary_Search, Big_O_Time_O(n*log_n)_Space_O(n) 318 82.28
0673 Number of Longest Increasing Subsequence Medium Array, Dynamic_Programming, Segment_Tree, Binary_Indexed_Tree 226 91.67

Day 17 Dynamic Programming
1143 Longest Common Subsequence Medium Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n*m)_Space_O(n*m) 307 38.36
0583 Delete Operation for Two Strings Medium String, Dynamic_Programming 197 100.00

Day 18 Dynamic Programming
0072 Edit Distance Medium Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n^2)_Space_O(n2) 182 92.16
0322 Coin Change Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Breadth_First_Search, Big_O_Time_O(m*n)_Space_O(amount) 332 50.68
0343 Integer Break Medium Dynamic_Programming, Math 218 63.89

Day 19 Bit Manipulation
0201 Bitwise AND of Numbers Range Medium Bit_Manipulation 368 80.00

Day 20 Others
0384 Shuffle an Array Medium Array, Math, Randomized 940 72.09

Day 21 Others
0202 Happy Number Easy Top_Interview_Questions, Hash_Table, Math, Two_Pointers 261 45.08
0149 Max Points on a Line Hard Top_Interview_Questions, Array, Hash_Table, Math, Geometry 307 83.33

Binary Search I

Day 1
0704 Binary Search Easy Top_100_Liked_Questions, Array, Binary_Search 261 77.91
0374 Guess Number Higher or Lower Easy Binary_Search, Interactive 134 94.19

Day 2
0035 Search Insert Position Easy Top_100_Liked_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 159 93.03
0852 Peak Index in a Mountain Array Medium Array, Binary_Search 433 94.29

Day 3
0367 Valid Perfect Square Easy Math, Binary_Search 137 94.55
1385 Find the Distance Value Between Two Arrays Easy Array, Sorting, Binary_Search, Two_Pointers 190 84.62

Day 4
0069 Sqrt(x) Easy Top_Interview_Questions, Math, Binary_Search 140 94.72
0744 Find Smallest Letter Greater Than Target Easy Array, Binary_Search 162 100.00

Day 5
0278 First Bad Version Easy Binary_Search, Interactive 349 76.86
0034 Find First and Last Position of Element in Sorted Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 174 100.00

Day 6
0441 Arranging Coins Easy Math, Binary_Search 150 84.21
1539 Kth Missing Positive Number Easy Array, Binary_Search 153 100.00

Day 7
0167 Two Sum II - Input Array Is Sorted Medium Array, Binary_Search, Two_Pointers 403 68.74
1608 Special Array With X Elements Greater Than or Equal X Easy Array, Sorting, Binary_Search 147 81.82

Day 8
1351 Count Negative Numbers in a Sorted Matrix Easy Array, Binary_Search, Matrix 206 71.43
0074 Search a 2D Matrix Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Big_O_Time_O(endRow+endCol)_Space_O(1) 159 74.46

Day 9
1337 The K Weakest Rows in a Matrix Easy Array, Sorting, Binary_Search, Matrix, Heap_Priority_Queue 216 77.59
1346 Check If N and Its Double Exist Easy Array, Hash_Table, Sorting, Binary_Search, Two_Pointers 175 70.83

Day 10
0350 Intersection of Two Arrays II Easy Array, Hash_Table, Sorting, Binary_Search, Two_Pointers 321 73.37
0633 Sum of Square Numbers Medium Math, Binary_Search, Two_Pointers 126 100.00

Day 11
1855 Maximum Distance Between a Pair of Values Medium Array, Greedy, Binary_Search, Two_Pointers 458 100.00
0033 Search in Rotated Sorted Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 151 93.77

Day 12
0153 Find Minimum in Rotated Sorted Array Medium Top_100_Liked_Questions, Array, Binary_Search, Big_O_Time_O(log_N)_Space_O(log_N) 262 60.96

Binary Search II

Day 1
0209 Minimum Size Subarray Sum Medium Array, Binary_Search, Prefix_Sum, Sliding_Window 315 96.73
0611 Valid Triangle Number Medium Array, Sorting, Greedy, Binary_Search, Two_Pointers 203 100.00

Day 2
0658 Find K Closest Elements Medium Array, Sorting, Binary_Search, Two_Pointers, Heap_Priority_Queue 375 95.16
1894 Find the Student that Will Replace the Chalk Medium Array, Binary_Search, Simulation, Prefix_Sum 520 50.00

Day 3
0300 Longest Increasing Subsequence Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Binary_Search, Big_O_Time_O(n*log_n)_Space_O(n) 318 82.28
1760 Minimum Limit of Balls in a Bag Medium Array, Binary_Search 460 100.00

Day 4
0875 Koko Eating Bananas Medium Array, Binary_Search 267 93.85
1552 Magnetic Force Between Two Balls Medium Array, Sorting, Binary_Search 636 100.00

Day 5
0287 Find the Duplicate Number Medium Top_100_Liked_Questions, Array, Binary_Search, Two_Pointers, Bit_Manipulation, Big_O_Time_O(n)_Space_O(n) 656 66.21
1283 Find the Smallest Divisor Given a Threshold Medium Array, Binary_Search 255 100.00

Day 6
1898 Maximum Number of Removable Characters Medium Array, String, Binary_Search 636 100.00
1870 Minimum Speed to Arrive on Time Medium Array, Binary_Search 628 50.00

Day 7
1482 Minimum Number of Days to Make m Bouquets Medium Array, Binary_Search 538 50.00
1818 Minimum Absolute Sum Difference Medium Array, Sorting, Binary_Search, Ordered_Set 447 100.00

Day 8
0240 Search a 2D Matrix II Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Divide_and_Conquer, Big_O_Time_O(n+m)_Space_O(1) 460 66.08
0275 H-Index II Medium Array, Binary_Search 398 81.82

Day 9
1838 Frequency of the Most Frequent Element Medium Array, Sorting, Greedy, Binary_Search, Prefix_Sum, Sliding_Window 564 88.89
0540 Single Element in a Sorted Array Medium Array, Binary_Search 274 86.67

Day 10
0222 Count Complete Tree Nodes
1712 Ways to Split Array Into Three Subarrays Medium Array, Binary_Search, Two_Pointers, Prefix_Sum 486 100.00

Day 11
0826 Most Profit Assigning Work Medium Array, Sorting, Greedy, Binary_Search, Two_Pointers 366 100.00
0436 Find Right Interval Medium Array, Sorting, Binary_Search 333 100.00

Day 12
0081 Search in Rotated Sorted Array II Medium Array, Binary_Search 170 96.30
0162 Find Peak Element Medium Top_Interview_Questions, Array, Binary_Search 297 53.85

Day 13
0154 Find Minimum in Rotated Sorted Array II Hard Array, Binary_Search 275 84.00
0528 Random Pick with Weight Medium Math, Binary_Search, Prefix_Sum, Randomized 393 91.38

Day 14
1508 Range Sum of Sorted Subarray Sums Medium Array, Sorting, Binary_Search, Two_Pointers 378 66.67
1574 Shortest Subarray to be Removed to Make Array Sorted Medium Array, Binary_Search, Two_Pointers, Stack, Monotonic_Stack 477 50.00

Day 15
1292 Maximum Side Length of a Square with Sum Less than or Equal to Threshold Medium Array, Binary_Search, Matrix, Prefix_Sum 376 100.00
1498 Number of Subsequences That Satisfy the Given Sum Condition Medium Array, Sorting, Binary_Search, Two_Pointers 487 97.89

Day 16
0981 Time Based Key-Value Store Medium String, Hash_Table, Binary_Search, Design 1011 65.56
1300 Sum of Mutated Array Closest to Target Medium Array, Sorting, Binary_Search 217 100.00

Day 17
1802 Maximum Value at a Given Index in a Bounded Array Medium Greedy, Binary_Search 118 100.00
1901 Find a Peak Element II Medium Array, Binary_Search, Matrix, Divide_and_Conquer 726 100.00

Day 18
1146 Snapshot Array Medium Array, Hash_Table, Binary_Search, Design 1064 57.14
1488 Avoid Flood in The City Medium Array, Hash_Table, Greedy, Binary_Search, Heap_Priority_Queue 823 66.67

Day 19
1562 Find Latest Group of Size M Medium Array, Binary_Search, Simulation 534 100.00
1648 Sell Diminishing-Valued Colored Balls Medium Array, Math, Sorting, Greedy, Binary_Search, Heap_Priority_Queue 509 100.00

Day 20
1201 Ugly Number III Medium Math, Binary_Search, Number_Theory 136 100.00
0911 Online Election Medium Array, Hash_Table, Binary_Search, Design 766 83.33

Dynamic Programming I

Day 1
0509 Fibonacci Number Easy Dynamic_Programming, Math, Recursion, Memoization 139 82.72
1137 N-th Tribonacci Number Easy Dynamic_Programming, Math, Memoization 122 69.35

Day 2
0070 Climbing Stairs Easy Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization, Big_O_Time_O(n)_Space_O(n) 124 71.98
0746 Min Cost Climbing Stairs Easy Array, Dynamic_Programming 171 96.76

Day 3
0198 House Robber Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 156 92.24
0213 House Robber II Medium Array, Dynamic_Programming 257 59.62
0740 Delete and Earn Medium Array, Hash_Table, Dynamic_Programming 192 100.00

Day 4
0055 Jump Game Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Greedy, Big_O_Time_O(n)_Space_O(1) 332 89.35
0045 Jump Game II Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Greedy, Big_O_Time_O(n)_Space_O(1) 208 93.37

Day 5
0053 Maximum Subarray Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Divide_and_Conquer, Big_O_Time_O(n)_Space_O(1) 510 78.81
0918 Maximum Sum Circular Subarray Medium Array, Dynamic_Programming, Divide_and_Conquer, Queue, Monotonic_Queue 339 86.96

Day 6
0152 Maximum Product Subarray Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 253 88.42
1567 Maximum Length of Subarray With Positive Product Medium Array, Dynamic_Programming, Greedy 468 33.33

Day 7
1014 Best Sightseeing Pair Medium Array, Dynamic_Programming 336 66.67
0121 Best Time to Buy and Sell Stock Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 609 94.06
0122 Best Time to Buy and Sell Stock II Medium Top_Interview_Questions, Array, Dynamic_Programming, Greedy 197 95.10

Day 8
0309 Best Time to Buy and Sell Stock with Cooldown Medium Array, Dynamic_Programming 272 73.33
0714 Best Time to Buy and Sell Stock with Transaction Fee Medium Array, Dynamic_Programming, Greedy 417 90.91

Day 9
0139 Word Break Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Big_O_Time_O(M+max*N)_Space_O(M+N+max) 197 87.17
0042 Trapping Rain Water Hard Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Two_Pointers, Stack, Monotonic_Stack, Big_O_Time_O(n)_Space_O(1) 189 99.37

Day 10
0413 Arithmetic Slices Medium Array, Dynamic_Programming 156 100.00
0091 Decode Ways Medium Top_Interview_Questions, String, Dynamic_Programming 148 79.07

Day 11
0264 Ugly Number II Medium Hash_Table, Dynamic_Programming, Math, Heap_Priority_Queue 182 95.45
0096 Unique Binary Search Trees Medium Dynamic_Programming, Math, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(n)_Space_O(1) 116 92.31

Day 12
0118 Pascal's Triangle Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming 277 33.22
0119 Pascal's Triangle II Easy Array, Dynamic_Programming 157 97.27

Day 13
0931 Minimum Falling Path Sum Medium Array, Dynamic_Programming, Matrix 201 84.21
0120 Triangle Medium Array, Dynamic_Programming 194 97.87

Day 14
1314 Matrix Block Sum Medium Array, Matrix, Prefix_Sum 235 100.00
0304 Range Sum Query 2D - Immutable Medium Array, Matrix, Design, Prefix_Sum 1373 85.71

Day 15
0062 Unique Paths Medium Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Combinatorics, Big_O_Time_O(m*n)_Space_O(m*n) 118 94.65
0063 Unique Paths II Medium Array, Dynamic_Programming, Matrix 151 81.94

Day 16
0064 Minimum Path Sum Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Matrix, Big_O_Time_O(m*n)_Space_O(m*n) 164 100.00
0221 Maximal Square Medium Array, Dynamic_Programming, Matrix, Big_O_Time_O(m*n)_Space_O(m*n) 614 44.00

Day 17
0005 Longest Palindromic Substring Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 162 99.00
0516 Longest Palindromic Subsequence Medium String, Dynamic_Programming 243 87.50

Day 18
0300 Longest Increasing Subsequence Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Binary_Search, Big_O_Time_O(n*log_n)_Space_O(n) 318 82.28
0376 Wiggle Subsequence Medium Array, Dynamic_Programming, Greedy 162 88.89

Day 19
0392 Is Subsequence Easy String, Dynamic_Programming, Two_Pointers 156 87.74
1143 Longest Common Subsequence Medium Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n*m)_Space_O(n*m) 307 38.36
0072 Edit Distance Medium Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n^2)_Space_O(n2) 182 92.16

Day 20
0322 Coin Change Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Breadth_First_Search, Big_O_Time_O(m*n)_Space_O(amount) 332 50.68
0518 Coin Change II Medium Array, Dynamic_Programming 139 100.00

Day 21
0377 Combination Sum IV Medium Array, Dynamic_Programming 217 72.41
0343 Integer Break Medium Dynamic_Programming, Math 218 63.89
0279 Perfect Squares Medium Dynamic_Programming, Math, Breadth_First_Search 176 98.80

Programming Skills I

Day 1 Basic Data Type
1523 Count Odd Numbers in an Interval Range Easy Math 114 97.22
1491 Average Salary Excluding the Minimum and Maximum Salary Easy Array, Sorting 137 91.67

Day 2 Operator
0191 Number of 1 Bits Easy Top_Interview_Questions, Bit_Manipulation 237 68.44
1281 Subtract the Product and Sum of Digits of an Integer Easy Math 128 61.82

Day 3 Conditional Statements
0976 Largest Perimeter Triangle Easy Array, Math, Sorting, Greedy 304 33.33
1779 Find Nearest Point That Has the Same X or Y Coordinate Easy Array 364 100.00

Day 4 Loop
1822 Sign of the Product of an Array Easy Array, Math 170 92.51
1502 Can Make Arithmetic Progression From Sequence Easy Array, Sorting 156 94.82
0202 Happy Number Easy Top_Interview_Questions, Hash_Table, Math, Two_Pointers 261 45.08
1790 Check if One String Swap Can Make Strings Equal Easy String, Hash_Table, Counting 138 100.00

Day 5 Function
0589 N-ary Tree Preorder Traversal Easy Depth_First_Search, Tree, Stack 233 84.02
0496 Next Greater Element I Easy Array, Hash_Table, Stack, Monotonic_Stack 171 100.00
1232 Check If It Is a Straight Line Easy Array, Math, Geometry 152 95.38

Day 6 Array
1588 Sum of All Odd Length Subarrays Easy Array, Math, Prefix_Sum 157 64.00
0283 Move Zeroes Easy Top_100_Liked_Questions, Array, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 516 79.07
1672 Richest Customer Wealth Easy Array, Matrix 155 94.54

Day 7 Array
1572 Matrix Diagonal Sum Easy Array, Matrix 221 67.61
0566 Reshape the Matrix Easy Array, Matrix, Simulation 239 99.05

Day 8 String
1768 Merge Strings Alternately Easy String, Two_Pointers 138 93.81
1678 Goal Parser Interpretation Easy String 136 88.24
0389 Find the Difference Easy String, Hash_Table, Sorting, Bit_Manipulation 256 64.81

Day 9 String
0709 To Lower Case Easy String 142 98.68
1309 Decrypt String from Alphabet to Integer Mapping Easy String 129 95.45
0953 Verifying an Alien Dictionary Easy Array, String, Hash_Table 137 100.00

Day 10 Linked List and Tree
1290 Convert Binary Number in a Linked List to Integer Easy Math, Linked_List 138 65.79
0876 Middle of the Linked List Easy Two_Pointers, Linked_List 136 76.52
0104 Maximum Depth of Binary Tree Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(H) 166 83.53
0404 Sum of Left Leaves Easy Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 173 86.05

Day 11 Containers and Libraries
1356 Sort Integers by The Number of 1 Bits Easy Array, Sorting, Bit_Manipulation, Counting 236 92.31
0232 Implement Queue using Stacks Easy Stack, Design, Queue 258 70.86
0242 Valid Anagram Easy String, Hash_Table, Sorting 251 87.65
0217 Contains Duplicate Easy Top_Interview_Questions, Array, Hash_Table, Sorting 719 73.49

Day 12 Class and Object
1603 Design Parking System Easy Design, Simulation, Counting 376 31.83
0303 Range Sum Query - Immutable Easy Array, Design, Prefix_Sum 472 63.64

Programming Skills II

Day 1
0896 Monotonic Array Easy Array 576 90.91
0028 Find the Index of the First Occurrence in a String Easy Top_Interview_Questions, String, Two_Pointers, String_Matching 126 97.58

Day 2
0110 Balanced Binary Tree Easy Depth_First_Search, Tree, Binary_Tree 182 71.30
0459 Repeated Substring Pattern Easy String, String_Matching 201 100.00

Day 3
0150 Evaluate Reverse Polish Notation Medium Top_Interview_Questions, Array, Math, Stack 233 88.82
0066 Plus One Easy Top_Interview_Questions, Array, Math 148 98.75

Day 4
1367 Linked List in Binary Tree Medium Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Linked_List 237 92.86
0043 Multiply Strings Medium String, Math, Simulation 165 96.72

Day 5
0067 Add Binary Easy String, Math, Bit_Manipulation, Simulation 164 90.60
0989 Add to Array-Form of Integer Easy Array, Math 350 70.00

Day 6
0739 Daily Temperatures Medium Top_100_Liked_Questions, Array, Stack, Monotonic_Stack, Big_O_Time_O(n)_Space_O(n) 936 80.54
0058 Length of Last Word Easy String 135 93.67

Day 7
0048 Rotate Image Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Math, Matrix, Big_O_Time_O(n^2)_Space_O(1) 160 90.11
1886 Determine Whether Matrix Can Be Obtained By Rotation Easy Array, Matrix 147 85.71

Day 8
0054 Spiral Matrix Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Matrix, Simulation 132 95.12
0973 K Closest Points to Origin Medium Array, Math, Sorting, Heap_Priority_Queue, Divide_and_Conquer, Geometry, Quickselect 800 37.89

Day 9
1630 Arithmetic Subarrays Medium Array, Sorting 264 100.00
0429 N-ary Tree Level Order Traversal Medium Breadth_First_Search, Tree 248 75.86

Day 10
0503 Next Greater Element II Medium Array, Stack, Monotonic_Stack 331 92.68
0556 Next Greater Element III Medium String, Math, Two_Pointers 137 80.00

Day 11
1376 Time Needed to Inform All Employees Medium Depth_First_Search, Breadth_First_Search, Tree 915 37.62
0049 Group Anagrams Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, String, Hash_Table, Sorting, Big_O_Time_O(n*k_log_k)_Space_O(n) 308 96.34

Day 12
0438 Find All Anagrams in a String Medium Top_100_Liked_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n+m)_Space_O(1) 561 54.68
0713 Subarray Product Less Than K Medium Array, Sliding_Window 336 92.11

Day 13
0304 Range Sum Query 2D - Immutable Medium Array, Matrix, Design, Prefix_Sum 1373 85.71
0910 Smallest Range II Medium Array, Math, Sorting, Greedy 234 100.00

Day 14
0143 Reorder List Medium Two_Pointers, Stack, Linked_List, Recursion 395 82.26
0138 Copy List with Random Pointer Medium Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Linked_List, Big_O_Time_O(N)_Space_O(N) 274 80.58

Day 15
0002 Add Two Numbers Medium Top_100_Liked_Questions, Top_Interview_Questions, Math, Linked_List, Recursion, Big_O_Time_O(max(N,M))_Space_O(max(N,M)), AI_can_be_used_to_solve_the_task 203 96.13
0445 Add Two Numbers II Medium Math, Stack, Linked_List 240 82.61

Day 16
0061 Rotate List Medium Two_Pointers, Linked_List 160 92.22
0173 Binary Search Tree Iterator Medium Tree, Binary_Tree, Stack, Design, Binary_Search_Tree, Iterator 563 46.91

Day 17
1845 Seat Reservation Manager Medium Design, Heap_Priority_Queue 834 100.00
0860 Lemonade Change Easy Array, Greedy 413 86.96

Day 18
0155 Min Stack Medium Top_100_Liked_Questions, Top_Interview_Questions, Stack, Design, Big_O_Time_O(1)_Space_O(N) 331 84.88
0341 Flatten Nested List Iterator Medium Depth_First_Search, Tree, Stack, Design, Queue, Iterator 210 100.00

Day 19
1797 Design Authentication Manager Medium Hash_Table, Design 334 100.00
0707 Design Linked List Medium Design, Linked_List 243 100.00

Day 20
0380 Insert Delete GetRandom O(1) Medium Array, Hash_Table, Math, Design, Randomized 1326 68.23
0622 Design Circular Queue Medium Array, Design, Linked_List, Queue 234 92.68
0729 My Calendar I Medium Binary_Search, Design, Ordered_Set, Segment_Tree 378 69.70

Graph Theory I

Day 1 Matrix Related Problems
0733 Flood Fill Easy Array, Depth_First_Search, Breadth_First_Search, Matrix 230 97.76
0200 Number of Islands Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find, Big_O_Time_O(M*N)_Space_O(M*N) 252 95.41

Day 2 Matrix Related Problems
0695 Max Area of Island Medium Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find 181 93.83
1254 Number of Closed Islands Medium Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find 177 89.47

Day 3 Matrix Related Problems
1020 Number of Enclaves Medium Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find 283 90.70
1905 Count Sub Islands Medium Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find 866 100.00

Day 4 Matrix Related Problems
1162 As Far from Land as Possible Medium Array, Dynamic_Programming, Breadth_First_Search, Matrix 362 81.25
0417 Pacific Atlantic Water Flow Medium Array, Depth_First_Search, Breadth_First_Search, Matrix 319 100.00

Day 5 Matrix Related Problems
1091 Shortest Path in Binary Matrix Medium Array, Breadth_First_Search, Matrix 305 98.28
0542 01 Matrix Medium Array, Dynamic_Programming, Breadth_First_Search, Matrix 441 94.06

Day 6 Matrix Related Problems
0934 Shortest Bridge Medium Array, Depth_First_Search, Breadth_First_Search, Matrix 301 80.95
1926 Nearest Exit from Entrance in Maze Medium Array, Breadth_First_Search, Matrix 351 94.44

Day 7 Standard Traversal
0797 All Paths From Source to Target Medium Depth_First_Search, Breadth_First_Search, Graph, Backtracking 232 100.00
0841 Keys and Rooms Medium Depth_First_Search, Breadth_First_Search, Graph 189 69.23

Day 8 Standard Traversal
0547 Number of Provinces Medium Depth_First_Search, Breadth_First_Search, Graph, Union_Find 229 79.73
1319 Number of Operations to Make Network Connected Medium Depth_First_Search, Breadth_First_Search, Graph, Union_Find 379 83.33

Day 9 Standard Traversal
1376 Time Needed to Inform All Employees Medium Depth_First_Search, Breadth_First_Search, Tree 915 37.62
0802 Find Eventual Safe States Medium Depth_First_Search, Breadth_First_Search, Graph, Topological_Sort 511 100.00

Day 10 Standard Traversal
1129 Shortest Path with Alternating Colors Medium Breadth_First_Search, Graph 208 80.00
1466 Reorder Routes to Make All Paths Lead to the City Zero Medium Depth_First_Search, Breadth_First_Search, Graph 718 100.00
0847 Shortest Path Visiting All Nodes Hard Dynamic_Programming, Breadth_First_Search, Bit_Manipulation, Graph, Bitmask 164 100.00

Day 11 Breadth First Search
1306 Jump Game III Medium Array, Depth_First_Search, Breadth_First_Search 291 100.00
1654 Minimum Jumps to Reach Home Medium Array, Dynamic_Programming, Breadth_First_Search 192 100.00
0365 Water and Jug Problem Medium Math, Depth_First_Search, Breadth_First_Search 130 100.00

Day 12 Breadth First Search
0433 Minimum Genetic Mutation Medium String, Hash_Table, Breadth_First_Search 204 82.08
0752 Open the Lock Medium Array, String, Hash_Table, Breadth_First_Search 310 100.00
0127 Word Ladder Hard Top_Interview_Questions, String, Hash_Table, Breadth_First_Search 396 98.68

Day 13 Graph Theory
0997 Find the Town Judge Easy Array, Hash_Table, Graph 475 58.62
1557 Minimum Number of Vertices to Reach All Nodes Medium Graph 792 99.29

Day 14 Graph Theory
1615 Maximal Network Rank Medium Graph 282 100.00
0886 Possible Bipartition Medium Depth_First_Search, Breadth_First_Search, Graph, Union_Find 397 100.00
0785 Is Graph Bipartite? Medium Depth_First_Search, Breadth_First_Search, Graph, Union_Find 215 82.35

SQL I

Day 1 Select
0595 Big Countries Easy Database 417 56.09
1757 Recyclable and Low Fat Products Easy Database 1237 34.20
0584 Find Customer Referee Easy Database 779 43.48
0183 Customers Who Never Order Easy Database 712 33.67

Day 2 Select and Order
1873 Calculate Special Bonus Easy Database 1321 33.12
0627 Swap Salary Easy Database 400 51.04
0196 Delete Duplicate Emails Easy Database 593 94.17

Day 3 String Processing Functions
1667 Fix Names in a Table Easy Database 1196 61.40
1484 Group Sold Products By The Date Easy LeetCode_Curated_SQL_70, Database 899 40.76
1527 Patients With a Condition Easy Database 708 48.23

Day 4 Union and Select
1965 Employees With Missing Information Easy Database 949 88.66
1795 Rearrange Products Table Easy Database 1027 67.57
0608 Tree Node Medium LeetCode_Curated_SQL_70, Database 794 48.38
0176 Second Highest Salary Medium Database 219 92.54

Day 5 Union
0175 Combine Two Tables Easy Database 473 54.97
1581 Customer Who Visited but Did Not Make Any Transactions Easy Database 2771 54.68
1148 Article Views I Easy LeetCode_Curated_SQL_70, Database 806 54.41

Day 6 Union
0197 Rising Temperature Easy Database 394 94.15
0607 Sales Person Easy LeetCode_Curated_SQL_70, Database 2142 44.56

Day 7 Function
1141 User Activity for the Past 30 Days I Easy LeetCode_Curated_SQL_70, Database 790 87.11
1693 Daily Leads and Partners Easy Database 1115 52.84
1729 Find Followers Count Easy Database 1228 38.04

Day 8 Function
0586 Customer Placing the Largest Number of Orders Easy LeetCode_Curated_SQL_70, Database 768 44.85
0511 Game Play Analysis I Easy LeetCode_Curated_SQL_70, Database 790 45.04
1890 The Latest Login in 2020 Easy Database 1280 43.62
1741 Find Total Time Spent by Each Employee Easy Database 1101 51.40

Day 9 Control of Flow
1393 Capital Gain/Loss Medium LeetCode_Curated_SQL_70, Database 990 47.36
1407 Top Travellers Easy LeetCode_Curated_SQL_70, Database 1394 98.43
1158 Market Analysis I Medium Database 2470 44.76

Day 10 Where
0182 Duplicate Emails Easy Database 396 68.40
1050 Actors and Directors Who Cooperated At Least Three Times Easy LeetCode_Curated_SQL_70, Database 629 81.02
1587 Bank Account Summary II Easy Database 1582 52.96
1084 Sales Analysis III Easy LeetCode_Curated_SQL_70, Database 1881 79.36

Level 1

Day 1 Prefix Sum
1480 Running Sum of 1d Array Easy Array, Prefix_Sum 161 84.80
0724 Find Pivot Index Easy Array, Prefix_Sum 255 88.92

Day 2 String
0205 Isomorphic Strings Easy String, Hash_Table 278 79.96
0392 Is Subsequence Easy String, Dynamic_Programming, Two_Pointers 156 87.74

Day 3 Linked List
0021 Merge Two Sorted Lists Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) 157 92.24
0206 Reverse Linked List Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(N)_Space_O(1) 279 45.78

Day 4 Linked List
0876 Middle of the Linked List Easy Two_Pointers, Linked_List 136 76.52
0142 Linked List Cycle II Medium Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) 192 63.39

Day 5 Greedy
0121 Best Time to Buy and Sell Stock Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 609 94.06
0409 Longest Palindrome Easy String, Hash_Table, Greedy 259 60.71

Day 6 Tree
0589 N-ary Tree Preorder Traversal Easy Depth_First_Search, Tree, Stack 233 84.02
0102 Binary Tree Level Order Traversal Medium Top_100_Liked_Questions, Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) 198 95.14

Day 7 Binary Search
0704 Binary Search Easy Top_100_Liked_Questions, Array, Binary_Search 261 77.91
0278 First Bad Version Easy Binary_Search, Interactive 349 76.86

Day 8 Binary Search Tree
0098 Validate Binary Search Tree Medium Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(N)_Space_O(log(N)) 190 61.62
0235 Lowest Common Ancestor of a Binary Search Tree Medium Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree 404 75.59

Day 9 Graph/BFS/DFS
0733 Flood Fill Easy Array, Depth_First_Search, Breadth_First_Search, Matrix 230 97.76
0200 Number of Islands Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find, Big_O_Time_O(M*N)_Space_O(M*N) 252 95.41

Day 10 Dynamic Programming
0509 Fibonacci Number Easy Dynamic_Programming, Math, Recursion, Memoization 139 82.72
0070 Climbing Stairs Easy Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization, Big_O_Time_O(n)_Space_O(n) 124 71.98

Day 11 Dynamic Programming
0746 Min Cost Climbing Stairs Easy Array, Dynamic_Programming 171 96.76
0062 Unique Paths Medium Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Combinatorics, Big_O_Time_O(m*n)_Space_O(m*n) 118 94.65

Day 12 Sliding Window/Two Pointer
0438 Find All Anagrams in a String Medium Top_100_Liked_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n+m)_Space_O(1) 561 54.68
0424 Longest Repeating Character Replacement Medium String, Hash_Table, Sliding_Window 288 84.38

Day 13 Hashmap
0001 Two Sum Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task 202 91.18
0299 Bulls and Cows Medium String, Hash_Table, Counting 254 84.82

Day 14 Stack
0844 Backspace String Compare Easy String, Two_Pointers, Stack, Simulation 126 98.31
0394 Decode String Medium Top_100_Liked_Questions, String, Stack, Recursion, Big_O_Time_O(n)_Space_O(n) 224 64.86

Day 15 Heap
1046 Last Stone Weight Easy Array, Heap_Priority_Queue 123 100.00
0692 Top K Frequent Words Medium String, Hash_Table, Sorting, Heap_Priority_Queue, Counting, Trie, Bucket_Sort 239 81.10

Level 2

Day 1 Implementation/Simulation
0202 Happy Number Easy Top_Interview_Questions, Hash_Table, Math, Two_Pointers 261 45.08
0054 Spiral Matrix Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Matrix, Simulation 132 95.12
1706 Where Will the Ball Fall Medium Array, Dynamic_Programming, Depth_First_Search, Matrix, Simulation 270 67.86

Day 2 String
0014 Longest Common Prefix Easy Top_100_Liked_Questions, Top_Interview_Questions, String 154 89.70
0043 Multiply Strings Medium String, Math, Simulation 165 96.72

Day 3 Linked List
0019 Remove Nth Node From End of List Medium Top_100_Liked_Questions, Top_Interview_Questions, Two_Pointers, Linked_List, Big_O_Time_O(L)_Space_O(L) 144 96.28
0234 Palindrome Linked List Easy Top_100_Liked_Questions, Two_Pointers, Stack, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(1) 641 79.53

Day 4 Linked List
0328 Odd Even Linked List Medium Linked_List 216 86.96
0148 Sort List Medium Top_100_Liked_Questions, Top_Interview_Questions, Sorting, Two_Pointers, Linked_List, Divide_and_Conquer, Merge_Sort, Big_O_Time_O(log(N))_Space_O(log(N)) 820 61.70

Day 5 Greedy
2131 Longest Palindrome by Concatenating Two Letter Words Medium Array, String, Hash_Table, Greedy, Counting 607 90.00
0621 Task Scheduler Medium Array, Hash_Table, Sorting, Greedy, Heap_Priority_Queue, Counting 266 98.36

Day 6 Tree
0226 Invert Binary Tree Easy Top_100_Liked_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 233 54.90
0110 Balanced Binary Tree Easy Depth_First_Search, Tree, Binary_Tree 182 71.30

Day 7 Tree
0543 Diameter of Binary Tree Easy Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 307 43.93
0437 Path Sum III Medium Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 403 54.12

Day 8 Binary Search
0074 Search a 2D Matrix Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Big_O_Time_O(endRow+endCol)_Space_O(1) 159 74.46
0033 Search in Rotated Sorted Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 151 93.77

Day 9 Binary Search Tree
0108 Convert Sorted Array to Binary Search Tree Easy Top_Interview_Questions, Array, Tree, Binary_Tree, Binary_Search_Tree, Divide_and_Conquer 167 80.29
0230 Kth Smallest Element in a BST Medium Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(n)_Space_O(n) 393 33.33
0173 Binary Search Tree Iterator Medium Tree, Binary_Tree, Stack, Design, Binary_Search_Tree, Iterator 563 46.91

Day 10 Graph/BFS/DFS
0994 Rotting Oranges Medium Top_100_Liked_Questions, Array, Breadth_First_Search, Matrix 164 82.95
0417 Pacific Atlantic Water Flow Medium Array, Depth_First_Search, Breadth_First_Search, Matrix 319 100.00

Day 11 Graph/BFS/DFS
0210 Course Schedule II Medium Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Graph, Topological_Sort 266 96.32
0815 Bus Routes Hard Array, Hash_Table, Breadth_First_Search 429 100.00

Day 12 Dynamic Programming
0198 House Robber Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 156 92.24
0322 Coin Change Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Breadth_First_Search, Big_O_Time_O(m*n)_Space_O(amount) 332 50.68

Day 13 Dynamic Programming
0416 Partition Equal Subset Sum Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Big_O_Time_O(n*sums)_Space_O(n*sums) 204 98.82
0152 Maximum Product Subarray Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 253 88.42

Day 14 Sliding Window/Two Pointer
0003 Longest Substring Without Repeating Characters Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n)_Space_O(1), AI_can_be_used_to_solve_the_task 201 87.28
0016 3Sum Closest Medium Array, Sorting, Two_Pointers 163 100.00
0076 Minimum Window Substring Hard Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(s.length())_Space_O(1) 191 96.38

Day 15 Tree
0100 Same Tree Easy Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 134 86.63
0101 Symmetric Tree Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(log(N)) 153 82.35
0199 Binary Tree Right Side View Medium Top_100_Liked_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 194 92.89

Day 16 Design
0232 Implement Queue using Stacks Easy Stack, Design, Queue 258 70.86
0155 Min Stack Medium Top_100_Liked_Questions, Top_Interview_Questions, Stack, Design, Big_O_Time_O(1)_Space_O(N) 331 84.88
0208 Implement Trie (Prefix Tree) Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Design, Trie, Big_O_Time_O(word.length())_or_O(prefix.length())_Space_O(N) 689 61.00

Day 17 Interval
0057 Insert Interval Medium Array 249 75.63
0056 Merge Intervals Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Big_O_Time_O(n_log_n)_Space_O(n) 334 80.67

Day 18 Stack
0735 Asteroid Collision Medium Array, Stack 243 100.00
0227 Basic Calculator II Medium String, Math, Stack 383 62.50

Day 19 Union Find
0547 Number of Provinces Medium Depth_First_Search, Breadth_First_Search, Graph, Union_Find 229 79.73
0947 Most Stones Removed with Same Row or Column Medium Depth_First_Search, Graph, Union_Find 200 100.00

Day 20 Brute Force/Backtracking
0039 Combination Sum Medium Top_100_Liked_Questions, Array, Backtracking, Big_O_Time_O(2^n)_Space_O(n+2^n) 226 88.89
0046 Permutations Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Backtracking, Big_O_Time_O(n*n!)_Space_O(n+n!) 188 99.00

Udemy

Udemy Integers
0412 Fizz Buzz Easy String, Math, Simulation 307 71.81
0136 Single Number Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) 344 83.63
0007 Reverse Integer Medium Top_Interview_Questions, Math 149 77.89
0009 Palindrome Number Easy Math 217 95.34
0172 Factorial Trailing Zeroes Medium Top_Interview_Questions, Math 220 67.65
0050 Pow(x, n) Medium Top_Interview_Questions, Math, Recursion 172 38.68

Udemy Strings
0344 Reverse String Easy String, Two_Pointers, Recursion 445 69.75
0014 Longest Common Prefix Easy Top_100_Liked_Questions, Top_Interview_Questions, String 154 89.70
0187 Repeated DNA Sequences Medium String, Hash_Table, Bit_Manipulation, Sliding_Window, Hash_Function, Rolling_Hash 319 79.03
0003 Longest Substring Without Repeating Characters Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Sliding_Window, Big_O_Time_O(n)_Space_O(1), AI_can_be_used_to_solve_the_task 201 87.28
0020 Valid Parentheses Easy Top_100_Liked_Questions, Top_Interview_Questions, String, Stack, Big_O_Time_O(n)_Space_O(n) 137 88.76
0005 Longest Palindromic Substring Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 162 99.00
0394 Decode String Medium Top_100_Liked_Questions, String, Stack, Recursion, Big_O_Time_O(n)_Space_O(n) 224 64.86
0242 Valid Anagram Easy String, Hash_Table, Sorting 251 87.65
0049 Group Anagrams Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, String, Hash_Table, Sorting, Big_O_Time_O(n*k_log_k)_Space_O(n) 308 96.34
0151 Reverse Words in a String Medium String, Two_Pointers 206 98.90
0273 Integer to English Words Hard String, Math, Recursion 273 82.93

Udemy Binary Search
0704 Binary Search Easy Top_100_Liked_Questions, Array, Binary_Search 261 77.91
0033 Search in Rotated Sorted Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Binary_Search, Big_O_Time_O(log_n)_Space_O(1) 151 93.77
0153 Find Minimum in Rotated Sorted Array Medium Top_100_Liked_Questions, Array, Binary_Search, Big_O_Time_O(log_N)_Space_O(log_N) 262 60.96

Udemy Arrays
0121 Best Time to Buy and Sell Stock Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 609 94.06
0283 Move Zeroes Easy Top_100_Liked_Questions, Array, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 516 79.07
0001 Two Sum Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task 202 91.18
0217 Contains Duplicate Easy Top_Interview_Questions, Array, Hash_Table, Sorting 719 73.49
0058 Length of Last Word Easy String 135 93.67
0605 Can Place Flowers Easy Array, Greedy 209 85.71
0122 Best Time to Buy and Sell Stock II Medium Top_Interview_Questions, Array, Dynamic_Programming, Greedy 197 95.10
0080 Remove Duplicates from Sorted Array II Medium Array, Two_Pointers 192 80.67
0189 Rotate Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Math, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 483 86.95
0055 Jump Game Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Greedy, Big_O_Time_O(n)_Space_O(1) 332 89.35
0075 Sort Colors Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 164 64.43
0066 Plus One Easy Top_Interview_Questions, Array, Math 148 98.75
0238 Product of Array Except Self Medium Top_100_Liked_Questions, Array, Prefix_Sum, Big_O_Time_O(n^2)_Space_O(n) 669 48.96
1291 Sequential Digits Medium Enumeration 114 100.00
0448 Find All Numbers Disappeared in an Array Easy Array, Hash_Table 394 100.00
0442 Find All Duplicates in an Array Medium Array, Hash_Table 480 73.81
0041 First Missing Positive Hard Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Big_O_Time_O(n)_Space_O(n) 357 97.17
0697 Degree of an Array Easy Array, Hash_Table 289 84.62
0532 K-diff Pairs in an Array Medium Array, Hash_Table, Sorting, Binary_Search, Two_Pointers 230 84.62
0713 Subarray Product Less Than K Medium Array, Sliding_Window 336 92.11
1007 Minimum Domino Rotations For Equal Row Medium Array, Greedy 421 50.00
1306 Jump Game III Medium Array, Depth_First_Search, Breadth_First_Search 291 100.00
0456 132 Pattern Medium Array, Binary_Search, Stack, Ordered_Set, Monotonic_Stack 434 100.00
0239 Sliding Window Maximum Hard Top_100_Liked_Questions, Array, Heap_Priority_Queue, Sliding_Window, Queue, Monotonic_Queue, Big_O_Time_O(n*k)_Space_O(n+k) 1059 86.14

Udemy Two Pointers
0392 Is Subsequence Easy String, Dynamic_Programming, Two_Pointers 156 87.74
0125 Valid Palindrome Easy Top_Interview_Questions, String, Two_Pointers 353 52.06
0977 Squares of a Sorted Array Easy Array, Sorting, Two_Pointers 271 77.17
0026 Remove Duplicates from Sorted Array Easy Top_Interview_Questions, Array, Two_Pointers 249 67.38
0042 Trapping Rain Water Hard Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Two_Pointers, Stack, Monotonic_Stack, Big_O_Time_O(n)_Space_O(1) 189 99.37
0015 3Sum Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n*log(n))_Space_O(n^2) 493 93.45

Udemy Famous Algorithm
0053 Maximum Subarray Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Divide_and_Conquer, Big_O_Time_O(n)_Space_O(1) 510 78.81
0169 Majority Element Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Sorting, Counting, Divide_and_Conquer, Big_O_Time_O(n)_Space_O(1) 460 51.25

Udemy Sorting Algorithms
0912 Sort an Array Medium Array, Sorting, Heap_Priority_Queue, Divide_and_Conquer, Merge_Sort, Bucket_Sort, Counting_Sort, Radix_Sort 606 98.48

Udemy 2D Arrays/Matrix
0304 Range Sum Query 2D - Immutable Medium Array, Matrix, Design, Prefix_Sum 1373 85.71
0074 Search a 2D Matrix Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Big_O_Time_O(endRow+endCol)_Space_O(1) 159 74.46
0054 Spiral Matrix Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Matrix, Simulation 132 95.12
0048 Rotate Image Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Math, Matrix, Big_O_Time_O(n^2)_Space_O(1) 160 90.11
1572 Matrix Diagonal Sum Easy Array, Matrix 221 67.61
0073 Set Matrix Zeroes Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Matrix, Big_O_Time_O(m*n)_Space_O(1) 248 97.33
0056 Merge Intervals Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Big_O_Time_O(n_log_n)_Space_O(n) 334 80.67

Udemy Linked List
0114 Flatten Binary Tree to Linked List Medium Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Linked_List, Big_O_Time_O(N)_Space_O(N) 191 93.10
0445 Add Two Numbers II Medium Math, Stack, Linked_List 240 82.61
0328 Odd Even Linked List Medium Linked_List 216 86.96
0061 Rotate List Medium Two_Pointers, Linked_List 160 92.22
0024 Swap Nodes in Pairs Medium Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(1) 149 44.20
0876 Middle of the Linked List Easy Two_Pointers, Linked_List 136 76.52
0142 Linked List Cycle II Medium Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) 192 63.39
0141 Linked List Cycle Easy Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) 223 91.85
0206 Reverse Linked List Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(N)_Space_O(1) 279 45.78
0021 Merge Two Sorted Lists Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) 157 92.24
0160 Intersection of Two Linked Lists Easy Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(M+N)_Space_O(1) 262 83.50
0234 Palindrome Linked List Easy Top_100_Liked_Questions, Two_Pointers, Stack, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(1) 641 79.53
0138 Copy List with Random Pointer Medium Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Linked_List, Big_O_Time_O(N)_Space_O(N) 274 80.58
0025 Reverse Nodes in k-Group Hard Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(k) 189 67.03
0146 LRU Cache Medium Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Design, Linked_List, Doubly_Linked_List, Big_O_Time_O(1)_Space_O(capacity) 1116 97.93
0707 Design Linked List Medium Design, Linked_List 243 100.00

Udemy Tree Stack Queue
0144 Binary Tree Preorder Traversal Easy Depth_First_Search, Tree, Binary_Tree, Stack 277 37.90
0094 Binary Tree Inorder Traversal Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Big_O_Time_O(n)_Space_O(n) 152 66.67
0145 Binary Tree Postorder Traversal Easy Depth_First_Search, Tree, Binary_Tree, Stack 211 80.00
0102 Binary Tree Level Order Traversal Medium Top_100_Liked_Questions, Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) 198 95.14
0103 Binary Tree Zigzag Level Order Traversal Medium Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree 176 71.62
0108 Convert Sorted Array to Binary Search Tree Easy Top_Interview_Questions, Array, Tree, Binary_Tree, Binary_Search_Tree, Divide_and_Conquer 167 80.29
1008 Construct Binary Search Tree from Preorder Traversal Medium Array, Tree, Binary_Tree, Stack, Monotonic_Stack, Binary_Search_Tree 145 100.00
0543 Diameter of Binary Tree Easy Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 307 43.93
0938 Range Sum of BST Easy Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree 356 55.36
0100 Same Tree Easy Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 134 86.63
0226 Invert Binary Tree Easy Top_100_Liked_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 233 54.90
0111 Minimum Depth of Binary Tree Easy Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 525 90.51
0104 Maximum Depth of Binary Tree Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(H) 166 83.53
0110 Balanced Binary Tree Easy Depth_First_Search, Tree, Binary_Tree 182 71.30
0701 Insert into a Binary Search Tree Medium Tree, Binary_Tree, Binary_Search_Tree 311 79.03
0297 Serialize and Deserialize Binary Tree Hard String, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Design 475 78.85
0124 Binary Tree Maximum Path Sum Hard Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) 331 74.42
0098 Validate Binary Search Tree Medium Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(N)_Space_O(log(N)) 190 61.62
0337 House Robber III Medium Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree 282 84.62
0236 Lowest Common Ancestor of a Binary Tree Medium Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 386 45.21
0968 Binary Tree Cameras Hard Dynamic_Programming, Depth_First_Search, Tree, Binary_Tree 176 100.00

Udemy Trie and Heap
0208 Implement Trie (Prefix Tree) Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Design, Trie, Big_O_Time_O(word.length())_or_O(prefix.length())_Space_O(N) 689 61.00
0745 Prefix and Suffix Search Hard String, Design, Trie 1638 100.00

Udemy Graph
0200 Number of Islands Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Depth_First_Search, Breadth_First_Search, Matrix, Union_Find, Big_O_Time_O(M*N)_Space_O(M*N) 252 95.41
0133 Clone Graph Medium Hash_Table, Depth_First_Search, Breadth_First_Search, Graph 351 60.91
0417 Pacific Atlantic Water Flow Medium Array, Depth_First_Search, Breadth_First_Search, Matrix 319 100.00

Udemy Dynamic Programming
0120 Triangle Medium Array, Dynamic_Programming 194 97.87
0118 Pascal's Triangle Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming 277 33.22
0119 Pascal's Triangle II Easy Array, Dynamic_Programming 157 97.27
0139 Word Break Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Dynamic_Programming, Trie, Memoization, Big_O_Time_O(M+max*N)_Space_O(M+N+max) 197 87.17
0152 Maximum Product Subarray Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 253 88.42
0198 House Robber Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 156 92.24
0213 House Robber II Medium Array, Dynamic_Programming 257 59.62
0509 Fibonacci Number Easy Dynamic_Programming, Math, Recursion, Memoization 139 82.72
0070 Climbing Stairs Easy Top_100_Liked_Questions, Top_Interview_Questions, Dynamic_Programming, Math, Memoization, Big_O_Time_O(n)_Space_O(n) 124 71.98
0064 Minimum Path Sum Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Matrix, Big_O_Time_O(m*n)_Space_O(m*n) 164 100.00
0300 Longest Increasing Subsequence Medium Top_100_Liked_Questions, Array, Dynamic_Programming, Binary_Search, Big_O_Time_O(n*log_n)_Space_O(n) 318 82.28
1143 Longest Common Subsequence Medium Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n*m)_Space_O(n*m) 307 38.36
0072 Edit Distance Medium Top_100_Liked_Questions, String, Dynamic_Programming, Big_O_Time_O(n^2)_Space_O(n2) 182 92.16
0044 Wildcard Matching Hard Top_Interview_Questions, String, Dynamic_Programming, Greedy, Recursion 220 84.85
0010 Regular Expression Matching Hard Top_Interview_Questions, String, Dynamic_Programming, Recursion, Big_O_Time_O(m*n)_Space_O(m*n) 171 85.26

Udemy Backtracking/Recursion
0022 Generate Parentheses Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Backtracking, Big_O_Time_O(2^n)_Space_O(n) 161 85.45
0039 Combination Sum Medium Top_100_Liked_Questions, Array, Backtracking, Big_O_Time_O(2^n)_Space_O(n+2^n) 226 88.89
0216 Combination Sum III Medium Array, Backtracking 175 90.91
0078 Subsets Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Backtracking, Big_O_Time_O(2^n)_Space_O(n*2^n) 171 94.92
0017 Letter Combinations of a Phone Number Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Hash_Table, Backtracking, Big_O_Time_O(4^n)_Space_O(n) 155 95.24
0046 Permutations Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Backtracking, Big_O_Time_O(n*n!)_Space_O(n+n!) 188 99.00

Udemy Bit Manipulation
0191 Number of 1 Bits Easy Top_Interview_Questions, Bit_Manipulation 237 68.44
0389 Find the Difference Easy String, Hash_Table, Sorting, Bit_Manipulation 256 64.81
0190 Reverse Bits Easy Top_Interview_Questions, Bit_Manipulation, Divide_and_Conquer 198 81.82
0461 Hamming Distance Easy Bit_Manipulation 150 96.15
1009 Complement of Base 10 Integer Easy Bit_Manipulation 126 72.73
0338 Counting Bits Easy Dynamic_Programming, Bit_Manipulation, Big_O_Time_O(num)_Space_O(num) 186 99.26
0371 Sum of Two Integers Medium Math, Bit_Manipulation 129 95.45
0029 Divide Two Integers Medium Top_Interview_Questions, Math, Bit_Manipulation 144 82.50

Udemy Design
0155 Min Stack Medium Top_100_Liked_Questions, Top_Interview_Questions, Stack, Design, Big_O_Time_O(1)_Space_O(N) 331 84.88

Data Structure I

Day 1 Array
0217 Contains Duplicate Easy Top_Interview_Questions, Array, Hash_Table, Sorting 719 73.49
0053 Maximum Subarray Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Divide_and_Conquer, Big_O_Time_O(n)_Space_O(1) 510 78.81

Day 2 Array
0001 Two Sum Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Big_O_Time_O(n)_Space_O(n), AI_can_be_used_to_solve_the_task 202 91.18
0088 Merge Sorted Array Easy Top_Interview_Questions, Array, Sorting, Two_Pointers 170 69.74

Day 3 Array
0350 Intersection of Two Arrays II Easy Array, Hash_Table, Sorting, Binary_Search, Two_Pointers 321 73.37
0121 Best Time to Buy and Sell Stock Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming, Big_O_Time_O(N)_Space_O(1) 609 94.06

Day 4 Array
0566 Reshape the Matrix Easy Array, Matrix, Simulation 239 99.05
0118 Pascal's Triangle Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Dynamic_Programming 277 33.22

Day 5 Array
0036 Valid Sudoku Medium Top_Interview_Questions, Array, Hash_Table, Matrix 181 95.15
0074 Search a 2D Matrix Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Big_O_Time_O(endRow+endCol)_Space_O(1) 159 74.46

Day 6 String
0387 First Unique Character in a String Easy String, Hash_Table, Counting, Queue 369 82.68
0383 Ransom Note Easy String, Hash_Table, Counting 333 79.58
0242 Valid Anagram Easy String, Hash_Table, Sorting 251 87.65

Day 7 Linked List
0141 Linked List Cycle Easy Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) 223 91.85
0021 Merge Two Sorted Lists Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(m+n)_Space_O(m+n) 157 92.24
0203 Remove Linked List Elements Easy Linked_List, Recursion 233 91.22

Day 8 Linked List
0206 Reverse Linked List Easy Top_100_Liked_Questions, Top_Interview_Questions, Linked_List, Recursion, Big_O_Time_O(N)_Space_O(1) 279 45.78
0083 Remove Duplicates from Sorted List Easy Linked_List 173 82.42

Day 9 Stack Queue
0020 Valid Parentheses Easy Top_100_Liked_Questions, Top_Interview_Questions, String, Stack, Big_O_Time_O(n)_Space_O(n) 137 88.76
0232 Implement Queue using Stacks Easy Stack, Design, Queue 258 70.86

Day 10 Tree
0144 Binary Tree Preorder Traversal Easy Depth_First_Search, Tree, Binary_Tree, Stack 277 37.90
0094 Binary Tree Inorder Traversal Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Stack, Big_O_Time_O(n)_Space_O(n) 152 66.67
0145 Binary Tree Postorder Traversal Easy Depth_First_Search, Tree, Binary_Tree, Stack 211 80.00

Day 11 Tree
0102 Binary Tree Level Order Traversal Medium Top_100_Liked_Questions, Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(N) 198 95.14
0104 Maximum Depth of Binary Tree Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(H) 166 83.53
0101 Symmetric Tree Easy Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(N)_Space_O(log(N)) 153 82.35

Day 12 Tree
0226 Invert Binary Tree Easy Top_100_Liked_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 233 54.90
0112 Path Sum Easy Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 322 36.41

Day 13 Tree
0700 Search in a Binary Search Tree Easy Tree, Binary_Tree, Binary_Search_Tree 251 88.31
0701 Insert into a Binary Search Tree Medium Tree, Binary_Tree, Binary_Search_Tree 311 79.03

Day 14 Tree
0098 Validate Binary Search Tree Medium Top_100_Liked_Questions, Top_Interview_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(N)_Space_O(log(N)) 190 61.62
0653 Two Sum IV - Input is a BST Easy Hash_Table, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Two_Pointers, Binary_Search_Tree 231 96.08
0235 Lowest Common Ancestor of a Binary Search Tree Medium Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree 404 75.59

Data Structure II

Day 1 Array
0136 Single Number Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Bit_Manipulation, Big_O_Time_O(N)_Space_O(1) 344 83.63
0169 Majority Element Easy Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Sorting, Counting, Divide_and_Conquer, Big_O_Time_O(n)_Space_O(1) 460 51.25
0015 3Sum Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n*log(n))_Space_O(n^2) 493 93.45

Day 2 Array
0075 Sort Colors Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 164 64.43
0056 Merge Intervals Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Big_O_Time_O(n_log_n)_Space_O(n) 334 80.67
0706 Design HashMap Easy Array, Hash_Table, Design, Linked_List, Hash_Function 405 92.11

Day 3 Array
0119 Pascal's Triangle II Easy Array, Dynamic_Programming 157 97.27
0048 Rotate Image Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Math, Matrix, Big_O_Time_O(n^2)_Space_O(1) 160 90.11
0059 Spiral Matrix II Medium Array, Matrix, Simulation 153 41.70

Day 4 Array
0240 Search a 2D Matrix II Medium Top_100_Liked_Questions, Array, Binary_Search, Matrix, Divide_and_Conquer, Big_O_Time_O(n+m)_Space_O(1) 460 66.08
0435 Non-overlapping Intervals Medium Array, Dynamic_Programming, Sorting, Greedy 1040 85.07

Day 5 Array
0334 Increasing Triplet Subsequence Medium Array, Greedy 672 60.61
0238 Product of Array Except Self Medium Top_100_Liked_Questions, Array, Prefix_Sum, Big_O_Time_O(n^2)_Space_O(n) 669 48.96
0560 Subarray Sum Equals K Medium Top_100_Liked_Questions, Array, Hash_Table, Prefix_Sum, Big_O_Time_O(n)_Space_O(n) 692 53.27

Day 6 String
0415 Add Strings Easy String, Math, Simulation 296 76.00
0409 Longest Palindrome Easy String, Hash_Table, Greedy 259 60.71

Day 7 String
0290 Word Pattern Easy String, Hash_Table 177 89.55
0763 Partition Labels Medium String, Hash_Table, Greedy, Two_Pointers, Big_O_Time_O(n)_Space_O(1) 235 84.75

Day 8 String
0049 Group Anagrams Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, String, Hash_Table, Sorting, Big_O_Time_O(n*k_log_k)_Space_O(n) 308 96.34
0043 Multiply Strings Medium String, Math, Simulation 165 96.72

Day 9 String
0187 Repeated DNA Sequences Medium String, Hash_Table, Bit_Manipulation, Sliding_Window, Hash_Function, Rolling_Hash 319 79.03
0005 Longest Palindromic Substring Medium Top_100_Liked_Questions, Top_Interview_Questions, String, Dynamic_Programming, Big_O_Time_O(n)_Space_O(n) 162 99.00

Day 10 Linked List
0002 Add Two Numbers Medium Top_100_Liked_Questions, Top_Interview_Questions, Math, Linked_List, Recursion, Big_O_Time_O(max(N,M))_Space_O(max(N,M)), AI_can_be_used_to_solve_the_task 203 96.13
0142 Linked List Cycle II Medium Top_100_Liked_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(N)_Space_O(1) 192 63.39

Day 11 Linked List
0160 Intersection of Two Linked Lists Easy Top_100_Liked_Questions, Top_Interview_Questions, Hash_Table, Two_Pointers, Linked_List, Big_O_Time_O(M+N)_Space_O(1) 262 83.50
0082 Remove Duplicates from Sorted List II Medium Two_Pointers, Linked_List 166 89.47

Day 12 Linked List
0024 Swap Nodes in Pairs Medium Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(1) 149 44.20
0707 Design Linked List Medium Design, Linked_List 243 100.00

Day 13 Linked List
0025 Reverse Nodes in k-Group Hard Top_100_Liked_Questions, Linked_List, Recursion, Big_O_Time_O(n)_Space_O(k) 189 67.03
0143 Reorder List Medium Two_Pointers, Stack, Linked_List, Recursion 395 82.26

Day 14 Stack Queue
0155 Min Stack Medium Top_100_Liked_Questions, Top_Interview_Questions, Stack, Design, Big_O_Time_O(1)_Space_O(N) 331 84.88
1249 Minimum Remove to Make Valid Parentheses Medium String, Stack 218 100.00
1823 Find the Winner of the Circular Game Medium Array, Math, Simulation, Recursion, Queue 119 87.50

Day 15 Tree
0108 Convert Sorted Array to Binary Search Tree Easy Top_Interview_Questions, Array, Tree, Binary_Tree, Binary_Search_Tree, Divide_and_Conquer 167 80.29
0105 Construct Binary Tree from Preorder and Inorder Traversal Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Hash_Table, Tree, Binary_Tree, Divide_and_Conquer, Big_O_Time_O(N)_Space_O(N) 183 95.45
0103 Binary Tree Zigzag Level Order Traversal Medium Top_Interview_Questions, Breadth_First_Search, Tree, Binary_Tree 176 71.62

Day 16 Tree
0199 Binary Tree Right Side View Medium Top_100_Liked_Questions, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree 194 92.89
0113 Path Sum II Medium Depth_First_Search, Tree, Binary_Tree, Backtracking 364 78.67
0450 Delete Node in a BST Medium Tree, Binary_Tree, Binary_Search_Tree 257 84.62

Day 17 Tree
0230 Kth Smallest Element in a BST Medium Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Binary_Search_Tree, Big_O_Time_O(n)_Space_O(n) 393 33.33
0173 Binary Search Tree Iterator Medium Tree, Binary_Tree, Stack, Design, Binary_Search_Tree, Iterator 563 46.91

Day 18 Tree
0236 Lowest Common Ancestor of a Binary Tree Medium Top_100_Liked_Questions, Depth_First_Search, Tree, Binary_Tree, Big_O_Time_O(n)_Space_O(n) 386 45.21
0297 Serialize and Deserialize Binary Tree Hard String, Depth_First_Search, Breadth_First_Search, Tree, Binary_Tree, Design 475 78.85

Day 19 Graph
0997 Find the Town Judge Easy Array, Hash_Table, Graph 475 58.62
1557 Minimum Number of Vertices to Reach All Nodes Medium Graph 792 99.29
0841 Keys and Rooms Medium Depth_First_Search, Breadth_First_Search, Graph 189 69.23

Day 20 Heap Priority Queue
0215 Kth Largest Element in an Array Medium Top_100_Liked_Questions, Top_Interview_Questions, Array, Sorting, Heap_Priority_Queue, Divide_and_Conquer, Quickselect, Big_O_Time_O(n*log(n))_Space_O(log(n)) 839 34.43
0347 Top K Frequent Elements Medium Top_100_Liked_Questions, Array, Hash_Table, Sorting, Heap_Priority_Queue, Counting, Divide_and_Conquer, Quickselect, Bucket_Sort, Big_O_Time_O(n*log(n))_Space_O(k) 268 99.74

Day 21 Heap Priority Queue
0451 Sort Characters By Frequency Medium String, Hash_Table, Sorting, Heap_Priority_Queue, Counting, Bucket_Sort 288 81.72
0973 K Closest Points to Origin Medium Array, Math, Sorting, Heap_Priority_Queue, Divide_and_Conquer, Geometry, Quickselect 800 37.89

Contributing

Your ideas/fixes/algorithms are more than welcome!

  1. Fork this repo
  2. Clone your forked repo (git clone https://github.com/YOUR_GITHUB_USERNAME/LeetCode-in-Kotlin.git) onto your local machine
  3. cd into your cloned directory, create your feature branch (git checkout -b my-awesome-fix)
  4. git add your desired changes to this repo
  5. Commit your changes (git commit -m 'Added some awesome features/fixes')
  6. Push to the branch (git push origin my-awesome-feature)
  7. Open your forked repo on Github website, create a new Pull Request to this repo!

About

Kotlin-based LeetCode algorithm problem solutions, regularly updated.

leetcode-in-kotlin.github.io

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kotlin algorithm math leetcode algorithm-competitions leetcode-solutions interview-questions dynamic-programming algorithms-and-data-structures leetcode-kotlin

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Version 1.31 Latest
Dec 1, 2024
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