list-04

Question	Free?	Status	Difficulty	Topics	Similar Questions
301. Remove Invalid Parentheses  🔗  📝	🆓		⭐️⭐️⭐️	String  🔗 Backtracking  🔗 Breadth-First Search  🔗	20. Valid Parentheses  🔗  📝 1963. Minimum Number of Swaps to Make the String Balanced  🔗  📝
302. Smallest Rectangle Enclosing Black Pixels  🔗  📝	💰		⭐️⭐️⭐️	Array  🔗 Binary Search  🔗 Depth-First Search  🔗 Breadth-First Search  🔗 Matrix  🔗
303. Range Sum Query - Immutable  🔗  📝	🆓	✅	⭐️	Array  🔗 Design  🔗 Prefix Sum  🔗	304. Range Sum Query 2D - Immutable  🔗  📝 307. Range Sum Query - Mutable  🔗  📝 325. Maximum Size Subarray Sum Equals k  🔗  📝
304. Range Sum Query 2D - Immutable  🔗  📝	🆓		⭐️⭐️	Array  🔗 Design  🔗 Matrix  🔗 Prefix Sum  🔗	303. Range Sum Query - Immutable  🔗  📝 308. Range Sum Query 2D - Mutable  🔗  📝
305. Number of Islands II  🔗  📝	💰		⭐️⭐️⭐️	Array  🔗 Union Find  🔗	200. Number of Islands  🔗  📝 2076. Process Restricted Friend Requests  🔗  📝
306. Additive Number  🔗  📝	🆓		⭐️⭐️	String  🔗 Backtracking  🔗	842. Split Array into Fibonacci Sequence  🔗  📝
307. Range Sum Query - Mutable  🔗  📝	🆓	👀	⭐️⭐️	Array  🔗 Design  🔗 Binary Indexed Tree  🔗 Segment Tree  🔗	303. Range Sum Query - Immutable  🔗  📝 308. Range Sum Query 2D - Mutable  🔗  📝
308. Range Sum Query 2D - Mutable  🔗  📝	💰		⭐️⭐️⭐️	Array  🔗 Design  🔗 Binary Indexed Tree  🔗 Segment Tree  🔗 Matrix  🔗	304. Range Sum Query 2D - Immutable  🔗  📝 307. Range Sum Query - Mutable  🔗  📝
309. Best Time to Buy and Sell Stock with Cooldown  🔗  📝	🆓		⭐️⭐️	Array  🔗 Dynamic Programming  🔗	121. Best Time to Buy and Sell Stock  🔗  📝 122. Best Time to Buy and Sell Stock II  🔗  📝
310. Minimum Height Trees  🔗  📝	🆓	👀	⭐️⭐️	Depth-First Search  🔗 Breadth-First Search  🔗 Graph  🔗 Topological Sort  🔗	207. Course Schedule  🔗  📝 210. Course Schedule II  🔗  📝
311. Sparse Matrix Multiplication  🔗  📝	💰		⭐️⭐️	Array  🔗 Hash Table  🔗 Matrix  🔗
312. Burst Balloons  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Dynamic Programming  🔗	1000. Minimum Cost to Merge Stones  🔗  📝
313. Super Ugly Number  🔗  📝	🆓	👀	⭐️⭐️	Array  🔗 Math  🔗 Dynamic Programming  🔗	264. Ugly Number II  🔗  📝
314. Binary Tree Vertical Order Traversal  🔗  📝	💰		⭐️⭐️	Hash Table  🔗 Tree  🔗 Depth-First Search  🔗 Breadth-First Search  🔗 Binary Tree  🔗	102. Binary Tree Level Order Traversal  🔗  📝
315. Count of Smaller Numbers After Self  🔗  📝	🆓	👀	⭐️⭐️⭐️	Array  🔗 Binary Search  🔗 Divide and Conquer  🔗 Binary Indexed Tree  🔗 Segment Tree  🔗 Merge Sort  🔗 Ordered Set  🔗	327. Count of Range Sum  🔗  📝 406. Queue Reconstruction by Height  🔗  📝 493. Reverse Pairs  🔗  📝 1365. How Many Numbers Are Smaller Than the Current Number  🔗  📝 2179. Count Good Triplets in an Array  🔗  📝
316. Remove Duplicate Letters  🔗  📝	🆓	✅	⭐️⭐️	String  🔗 Stack  🔗 Greedy  🔗 Monotonic Stack  🔗	2030. Smallest K-Length Subsequence With Occurrences of a Letter  🔗  📝
317. Shortest Distance from All Buildings  🔗  📝	💰		⭐️⭐️⭐️	Array  🔗 Breadth-First Search  🔗 Matrix  🔗	286. Walls and Gates  🔗  📝 296. Best Meeting Point  🔗  📝 1162. As Far from Land as Possible  🔗  📝
318. Maximum Product of Word Lengths  🔗  📝	🆓	✅	⭐️⭐️	Array  🔗 String  🔗 Bit Manipulation  🔗
319. Bulb Switcher  🔗  📝	🆓		⭐️⭐️	Math  🔗 Brainteaser  🔗	672. Bulb Switcher II  🔗  📝 995. Minimum Number of K Consecutive Bit Flips  🔗  📝 1375. Number of Times Binary String Is Prefix-Aligned  🔗  📝
320. Generalized Abbreviation  🔗  📝	💰		⭐️⭐️	String  🔗 Backtracking  🔗 Bit Manipulation  🔗	78. Subsets  🔗  📝 288. Unique Word Abbreviation  🔗  📝 411. Minimum Unique Word Abbreviation  🔗  📝
321. Create Maximum Number  🔗  📝	🆓		⭐️⭐️⭐️	Stack  🔗 Greedy  🔗 Monotonic Stack  🔗	402. Remove K Digits  🔗  📝 670. Maximum Swap  🔗  📝
322. Coin Change  🔗  📝	🆓	✅	⭐️⭐️	Array  🔗 Dynamic Programming  🔗 Breadth-First Search  🔗	983. Minimum Cost For Tickets  🔗  📝 2218. Maximum Value of K Coins From Piles  🔗  📝 2224. Minimum Number of Operations to Convert Time  🔗  📝
323. Number of Connected Components in an Undirected Graph  🔗  📝	💰		⭐️⭐️	Depth-First Search  🔗 Breadth-First Search  🔗 Union Find  🔗 Graph  🔗	200. Number of Islands  🔗  📝 261. Graph Valid Tree  🔗  📝 547. Number of Provinces  🔗  📝 2077. Paths in Maze That Lead to Same Room  🔗  📝
324. Wiggle Sort II  🔗  📝	🆓		⭐️⭐️	Array  🔗 Divide and Conquer  🔗 Sorting  🔗 Quickselect  🔗	75. Sort Colors  🔗  📝 215. Kth Largest Element in an Array  🔗  📝 280. Wiggle Sort  🔗  📝 1968. Array With Elements Not Equal to Average of Neighbors  🔗  📝
325. Maximum Size Subarray Sum Equals k  🔗  📝	💰		⭐️⭐️	Array  🔗 Hash Table  🔗	209. Minimum Size Subarray Sum  🔗  📝 303. Range Sum Query - Immutable  🔗  📝 525. Contiguous Array  🔗  📝 713. Subarray Product Less Than K  🔗  📝
326. Power of Three  🔗  📝	🆓	👀	⭐️	Math  🔗 Recursion  🔗	231. Power of Two  🔗  📝 342. Power of Four  🔗  📝 1780. Check if Number is a Sum of Powers of Three  🔗  📝
327. Count of Range Sum  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Binary Search  🔗 Divide and Conquer  🔗 Binary Indexed Tree  🔗 Segment Tree  🔗 Merge Sort  🔗 Ordered Set  🔗	315. Count of Smaller Numbers After Self  🔗  📝 493. Reverse Pairs  🔗  📝
328. Odd Even Linked List  🔗  📝	🆓		⭐️⭐️	Linked List  🔗	725. Split Linked List in Parts  🔗  📝
329. Longest Increasing Path in a Matrix  🔗  📝	🆓	✅	⭐️⭐️⭐️	Array  🔗 Dynamic Programming  🔗 Depth-First Search  🔗 Breadth-First Search  🔗 Graph  🔗 Topological Sort  🔗 Memoization  🔗 Matrix  🔗	2328. Number of Increasing Paths in a Grid  🔗  📝
330. Patching Array  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Greedy  🔗	1798. Maximum Number of Consecutive Values You Can Make  🔗  📝
331. Verify Preorder Serialization of a Binary Tree  🔗  📝	🆓		⭐️⭐️	String  🔗 Stack  🔗 Tree  🔗 Binary Tree  🔗
332. Reconstruct Itinerary  🔗  📝	🆓		⭐️⭐️⭐️	Depth-First Search  🔗 Graph  🔗 Eulerian Circuit  🔗	1923. Longest Common Subpath  🔗  📝 2097. Valid Arrangement of Pairs  🔗  📝
333. Largest BST Subtree  🔗  📝	💰		⭐️⭐️	Dynamic Programming  🔗 Tree  🔗 Depth-First Search  🔗 Binary Search Tree  🔗 Binary Tree  🔗
334. Increasing Triplet Subsequence  🔗  📝	🆓		⭐️⭐️	Array  🔗 Greedy  🔗	300. Longest Increasing Subsequence  🔗  📝 1995. Count Special Quadruplets  🔗  📝 2179. Count Good Triplets in an Array  🔗  📝
335. Self Crossing  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Math  🔗 Geometry  🔗
336. Palindrome Pairs  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Hash Table  🔗 String  🔗 Trie  🔗	5. Longest Palindromic Substring  🔗  📝 214. Shortest Palindrome  🔗  📝 2131. Longest Palindrome by Concatenating Two Letter Words  🔗  📝
337. House Robber III  🔗  📝	🆓	✅	⭐️⭐️	Dynamic Programming  🔗 Tree  🔗 Depth-First Search  🔗 Binary Tree  🔗	198. House Robber  🔗  📝 213. House Robber II  🔗  📝
338. Counting Bits  🔗  📝	🆓	✅	⭐️	Dynamic Programming  🔗 Bit Manipulation  🔗	191. Number of 1 Bits  🔗  📝
339. Nested List Weight Sum  🔗  📝	💰		⭐️⭐️	Depth-First Search  🔗 Breadth-First Search  🔗	364. Nested List Weight Sum II  🔗  📝 565. Array Nesting  🔗  📝 690. Employee Importance  🔗  📝
340. Longest Substring with At Most K Distinct Characters  🔗  📝	💰		⭐️⭐️	Hash Table  🔗 String  🔗 Sliding Window  🔗	3. Longest Substring Without Repeating Characters  🔗  📝 159. Longest Substring with At Most Two Distinct Characters  🔗  📝 424. Longest Repeating Character Replacement  🔗  📝 992. Subarrays with K Different Integers  🔗  📝 1004. Max Consecutive Ones III  🔗  📝 2024. Maximize the Confusion of an Exam  🔗  📝
341. Flatten Nested List Iterator  🔗  📝	🆓	✅	⭐️⭐️	Stack  🔗 Tree  🔗 Depth-First Search  🔗 Design  🔗 Queue  🔗 Iterator  🔗	251. Flatten 2D Vector  🔗  📝 281. Zigzag Iterator  🔗  📝 385. Mini Parser  🔗  📝 565. Array Nesting  🔗  📝
342. Power of Four  🔗  📝	🆓	✅	⭐️	Math  🔗 Bit Manipulation  🔗 Recursion  🔗	231. Power of Two  🔗  📝 326. Power of Three  🔗  📝
343. Integer Break  🔗  📝	🆓	✅	⭐️⭐️	Math  🔗 Dynamic Programming  🔗	1808. Maximize Number of Nice Divisors  🔗  📝
344. Reverse String  🔗  📝	🆓	✅	⭐️	Two Pointers  🔗 String  🔗 Recursion  🔗	345. Reverse Vowels of a String  🔗  📝 541. Reverse String II  🔗  📝
345. Reverse Vowels of a String  🔗  📝	🆓	✅	⭐️	Two Pointers  🔗 String  🔗	344. Reverse String  🔗  📝 1119. Remove Vowels from a String  🔗  📝
346. Moving Average from Data Stream  🔗  📝	💰		⭐️	Array  🔗 Design  🔗 Queue  🔗 Data Stream  🔗	2090. K Radius Subarray Averages  🔗  📝
347. Top K Frequent Elements  🔗  📝	🆓	✅	⭐️⭐️	Array  🔗 Hash Table  🔗 Divide and Conquer  🔗 Sorting  🔗 Heap (Priority Queue)  🔗 Bucket Sort  🔗 Counting  🔗 Quickselect  🔗	192. Word Frequency  🔗  📝 215. Kth Largest Element in an Array  🔗  📝 451. Sort Characters By Frequency  🔗  📝 659. Split Array into Consecutive Subsequences  🔗  📝 692. Top K Frequent Words  🔗  📝 973. K Closest Points to Origin  🔗  📝 1772. Sort Features by Popularity  🔗  📝 2284. Sender With Largest Word Count  🔗  📝
348. Design Tic-Tac-Toe  🔗  📝	💰		⭐️⭐️	Array  🔗 Hash Table  🔗 Design  🔗 Matrix  🔗	794. Valid Tic-Tac-Toe State  🔗  📝
349. Intersection of Two Arrays  🔗  📝	🆓	✅	⭐️	Array  🔗 Hash Table  🔗 Two Pointers  🔗 Binary Search  🔗 Sorting  🔗	350. Intersection of Two Arrays II  🔗  📝 1213. Intersection of Three Sorted Arrays  🔗  📝 2085. Count Common Words With One Occurrence  🔗  📝 2143. Choose Numbers From Two Arrays in Range  🔗  📝 2215. Find the Difference of Two Arrays  🔗  📝 2248. Intersection of Multiple Arrays  🔗  📝
350. Intersection of Two Arrays II  🔗  📝	🆓	✅	⭐️	Array  🔗 Hash Table  🔗 Two Pointers  🔗 Binary Search  🔗 Sorting  🔗	349. Intersection of Two Arrays  🔗  📝 1002. Find Common Characters  🔗  📝 2143. Choose Numbers From Two Arrays in Range  🔗  📝 2215. Find the Difference of Two Arrays  🔗  📝 2248. Intersection of Multiple Arrays  🔗  📝
351. Android Unlock Patterns  🔗  📝	💰		⭐️⭐️	Dynamic Programming  🔗 Backtracking  🔗
352. Data Stream as Disjoint Intervals  🔗  📝	🆓		⭐️⭐️⭐️	Binary Search  🔗 Design  🔗 Ordered Set  🔗	228. Summary Ranges  🔗  📝 436. Find Right Interval  🔗  📝 715. Range Module  🔗  📝 2276. Count Integers in Intervals  🔗  📝
353. Design Snake Game  🔗  📝	💰		⭐️⭐️	Array  🔗 Design  🔗 Queue  🔗 Matrix  🔗
354. Russian Doll Envelopes  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Binary Search  🔗 Dynamic Programming  🔗 Sorting  🔗	300. Longest Increasing Subsequence  🔗  📝 1996. The Number of Weak Characters in the Game  🔗  📝
355. Design Twitter  🔗  📝	🆓		⭐️⭐️	Hash Table  🔗 Linked List  🔗 Design  🔗 Heap (Priority Queue)  🔗	1500. Design a File Sharing System  🔗  📝
356. Line Reflection  🔗  📝	💰		⭐️⭐️	Array  🔗 Hash Table  🔗 Math  🔗	149. Max Points on a Line  🔗  📝 447. Number of Boomerangs  🔗  📝
357. Count Numbers with Unique Digits  🔗  📝	🆓	✅	⭐️⭐️	Math  🔗 Dynamic Programming  🔗 Backtracking  🔗
358. Rearrange String k Distance Apart  🔗  📝	💰		⭐️⭐️⭐️	Hash Table  🔗 String  🔗 Greedy  🔗 Sorting  🔗 Heap (Priority Queue)  🔗 Counting  🔗	621. Task Scheduler  🔗  📝 767. Reorganize String  🔗  📝 2182. Construct String With Repeat Limit  🔗  📝
359. Logger Rate Limiter  🔗  📝	💰		⭐️	Hash Table  🔗 Design  🔗	362. Design Hit Counter  🔗  📝
360. Sort Transformed Array  🔗  📝	💰		⭐️⭐️	Array  🔗 Math  🔗 Two Pointers  🔗 Sorting  🔗	977. Squares of a Sorted Array  🔗  📝
361. Bomb Enemy  🔗  📝	💰		⭐️⭐️	Array  🔗 Dynamic Programming  🔗 Matrix  🔗	2087. Minimum Cost Homecoming of a Robot in a Grid  🔗  📝 2132. Stamping the Grid  🔗  📝 2245. Maximum Trailing Zeros in a Cornered Path  🔗  📝 2257. Count Unguarded Cells in the Grid  🔗  📝
362. Design Hit Counter  🔗  📝	💰		⭐️⭐️	Array  🔗 Hash Table  🔗 Binary Search  🔗 Design  🔗 Queue  🔗	359. Logger Rate Limiter  🔗  📝
363. Max Sum of Rectangle No Larger Than K  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Binary Search  🔗 Matrix  🔗 Prefix Sum  🔗 Ordered Set  🔗
364. Nested List Weight Sum II  🔗  📝	💰		⭐️⭐️	Stack  🔗 Depth-First Search  🔗 Breadth-First Search  🔗	339. Nested List Weight Sum  🔗  📝 565. Array Nesting  🔗  📝
365. Water and Jug Problem  🔗  📝	🆓		⭐️⭐️	Math  🔗 Depth-First Search  🔗 Breadth-First Search  🔗
366. Find Leaves of Binary Tree  🔗  📝	💰		⭐️⭐️	Tree  🔗 Depth-First Search  🔗 Binary Tree  🔗
367. Valid Perfect Square  🔗  📝	🆓	✅	⭐️	Math  🔗 Binary Search  🔗	69. Sqrt(x)  🔗  📝 633. Sum of Square Numbers  🔗  📝
368. Largest Divisible Subset  🔗  📝	🆓		⭐️⭐️	Array  🔗 Math  🔗 Dynamic Programming  🔗 Sorting  🔗
369. Plus One Linked List  🔗  📝	💰		⭐️⭐️	Linked List  🔗 Math  🔗	66. Plus One  🔗  📝
370. Range Addition  🔗  📝	💰		⭐️⭐️	Array  🔗 Prefix Sum  🔗	598. Range Addition II  🔗  📝 2237. Count Positions on Street With Required Brightness  🔗  📝
371. Sum of Two Integers  🔗  📝	🆓	✅	⭐️⭐️	Math  🔗 Bit Manipulation  🔗	2. Add Two Numbers  🔗  📝
372. Super Pow  🔗  📝	🆓		⭐️⭐️	Math  🔗 Divide and Conquer  🔗	50. Pow(x, n)  🔗  📝
373. Find K Pairs with Smallest Sums  🔗  📝	🆓		⭐️⭐️	Array  🔗 Heap (Priority Queue)  🔗	378. Kth Smallest Element in a Sorted Matrix  🔗  📝 719. Find K-th Smallest Pair Distance  🔗  📝 2040. Kth Smallest Product of Two Sorted Arrays  🔗  📝
374. Guess Number Higher or Lower  🔗  📝	🆓	✅	⭐️	Binary Search  🔗 Interactive  🔗	278. First Bad Version  🔗  📝 375. Guess Number Higher or Lower II  🔗  📝 658. Find K Closest Elements  🔗  📝
375. Guess Number Higher or Lower II  🔗  📝	🆓		⭐️⭐️	Math  🔗 Dynamic Programming  🔗 Game Theory  🔗	294. Flip Game II  🔗  📝 374. Guess Number Higher or Lower  🔗  📝 464. Can I Win  🔗  📝 658. Find K Closest Elements  🔗  📝
376. Wiggle Subsequence  🔗  📝	🆓		⭐️⭐️	Array  🔗 Dynamic Programming  🔗 Greedy  🔗	2149. Rearrange Array Elements by Sign  🔗  📝
377. Combination Sum IV  🔗  📝	🆓	👀	⭐️⭐️	Array  🔗 Dynamic Programming  🔗	39. Combination Sum  🔗  📝
378. Kth Smallest Element in a Sorted Matrix  🔗  📝	🆓		⭐️⭐️	Array  🔗 Binary Search  🔗 Sorting  🔗 Heap (Priority Queue)  🔗 Matrix  🔗	373. Find K Pairs with Smallest Sums  🔗  📝 668. Kth Smallest Number in Multiplication Table  🔗  📝 719. Find K-th Smallest Pair Distance  🔗  📝 786. K-th Smallest Prime Fraction  🔗  📝
379. Design Phone Directory  🔗  📝	💰		⭐️⭐️	Array  🔗 Hash Table  🔗 Linked List  🔗 Design  🔗 Queue  🔗	1845. Seat Reservation Manager  🔗  📝
380. Insert Delete GetRandom O(1)  🔗  📝	🆓		⭐️⭐️	Array  🔗 Hash Table  🔗 Math  🔗 Design  🔗 Randomized  🔗	381. Insert Delete GetRandom O(1) - Duplicates allowed  🔗  📝
381. Insert Delete GetRandom O(1) - Duplicates allowed  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Hash Table  🔗 Math  🔗 Design  🔗 Randomized  🔗	380. Insert Delete GetRandom O(1)  🔗  📝
382. Linked List Random Node  🔗  📝	🆓	✅	⭐️⭐️	Linked List  🔗 Math  🔗 Reservoir Sampling  🔗 Randomized  🔗	398. Random Pick Index  🔗  📝
383. Ransom Note  🔗  📝	🆓	✅	⭐️	Hash Table  🔗 String  🔗 Counting  🔗	691. Stickers to Spell Word  🔗  📝
384. Shuffle an Array  🔗  📝	🆓		⭐️⭐️	Array  🔗 Math  🔗 Randomized  🔗
385. Mini Parser  🔗  📝	🆓		⭐️⭐️	String  🔗 Stack  🔗 Depth-First Search  🔗	341. Flatten Nested List Iterator  🔗  📝 439. Ternary Expression Parser  🔗  📝 722. Remove Comments  🔗  📝
386. Lexicographical Numbers  🔗  📝	🆓	✅	⭐️⭐️	Depth-First Search  🔗 Trie  🔗
387. First Unique Character in a String  🔗  📝	🆓	✅	⭐️	Hash Table  🔗 String  🔗 Queue  🔗 Counting  🔗	451. Sort Characters By Frequency  🔗  📝 2351. First Letter to Appear Twice  🔗  📝
388. Longest Absolute File Path  🔗  📝	🆓		⭐️⭐️	String  🔗 Stack  🔗 Depth-First Search  🔗
389. Find the Difference  🔗  📝	🆓	✅	⭐️	Hash Table  🔗 String  🔗 Bit Manipulation  🔗 Sorting  🔗	136. Single Number  🔗  📝
390. Elimination Game  🔗  📝	🆓		⭐️⭐️	Math  🔗 Recursion  🔗	2293. Min Max Game  🔗  📝
391. Perfect Rectangle  🔗  📝	🆓		⭐️⭐️⭐️	Array  🔗 Line Sweep  🔗
392. Is Subsequence  🔗  📝	🆓	✅	⭐️	Two Pointers  🔗 String  🔗 Dynamic Programming  🔗	792. Number of Matching Subsequences  🔗  📝 1055. Shortest Way to Form String  🔗  📝
393. UTF-8 Validation  🔗  📝	🆓		⭐️⭐️	Array  🔗 Bit Manipulation  🔗
394. Decode String  🔗  📝	🆓		⭐️⭐️	String  🔗 Stack  🔗 Recursion  🔗	471. Encode String with Shortest Length  🔗  📝 726. Number of Atoms  🔗  📝 1087. Brace Expansion  🔗  📝
395. Longest Substring with At Least K Repeating Characters  🔗  📝	🆓		⭐️⭐️	Hash Table  🔗 String  🔗 Divide and Conquer  🔗 Sliding Window  🔗	2014. Longest Subsequence Repeated k Times  🔗  📝 2067. Number of Equal Count Substrings  🔗  📝
396. Rotate Function  🔗  📝	🆓	👀	⭐️⭐️	Array  🔗 Math  🔗 Dynamic Programming  🔗
397. Integer Replacement  🔗  📝	🆓	✅	⭐️⭐️	Dynamic Programming  🔗 Greedy  🔗 Bit Manipulation  🔗 Memoization  🔗
398. Random Pick Index  🔗  📝	🆓	✅	⭐️⭐️	Hash Table  🔗 Math  🔗 Reservoir Sampling  🔗 Randomized  🔗	382. Linked List Random Node  🔗  📝 528. Random Pick with Weight  🔗  📝 710. Random Pick with Blacklist  🔗  📝
399. Evaluate Division  🔗  📝	🆓		⭐️⭐️	Array  🔗 Depth-First Search  🔗 Breadth-First Search  🔗 Union Find  🔗 Graph  🔗 Shortest Path  🔗	2307. Check for Contradictions in Equations  🔗  📝
400. Nth Digit  🔗  📝	🆓	✅	⭐️⭐️	Math  🔗 Binary Search  🔗