Hackerrank Practice Problems

• This repository contains solutions to Hackerrank practice problems in SQL, C++, Java or Python.
• If you are interested in adding more Hackerrank problem solutions, please feel free to contribute.
• If you feel this repo is helpful for you, please do star it.
• If you are a hacktoberfest contributor, claim only one issue at a time from this repository and a maximum of two issues for hacktoberfest contribution.
• Kindly follow CODE_OF_CONDUCT.md and CONTRIBUTING.md before contributing.
• Happy Coding 🥳!

Topics

SQL

• Basic Select
• Advanced Select
• Aggregation
• Basic Join
• Advanced Join
• Alternative Queries

C++

• Introduction
• Strings
• Classes
• STL
• Inheritance
• Debugging
• Other Concepts

Java

• Introduction
• Strings
• BigNumber
• Data Structures
• Object Oriented Programming
• Exception Handling
• Advanced

Python

• Introduction
• Basic Data Types
• Strings
• Sets
• Math
• Itertools
• Collections
• Date and Time
• Errors and Exceptions
• Classes
• Built-Ins
• Python Functionals
• Regex and Parsing
• XML
• Closures and Decorators
• Numpy
• Debugging

SQL (All the solutions are given in MySQL)

Basic Select

S.No.	Problem	Solution	Score	Difficulty
01.	Revising the Select Query I	Solution	10	Easy
02.	Revising the Select Query II	Solution	10	Easy
03.	Select All	Solution	10	Easy
04.	Select By ID	Solution	10	Easy
05.	Japanese Cities' Attributes	Solution	10	Easy
06.	Japanese Cities' Names	Solution	10	Easy
07.	Weather Observation Station 1	Solution	15	Easy
08.	Weather Observation Station 3	Solution	10	Easy
09.	Weather Observation Station 4	Solution	10	Easy
10.	Weather Observation Station 5	Solution	30	Easy
11.	Weather Observation Station 6	Solution	10	Easy
12.	Weather Observation Station 7	Solution	10	Easy
13.	Weather Observation Station 8	Solution	15	Easy
14.	Weather Observation Station 9	Solution	10	Easy
15.	Weather Observation Station 10	Solution	10	Easy
16.	Weather Observation Station 11	Solution	15	Easy
17.	Weather Observation Station 12	Solution	15	Easy
18.	Higher Than 75 Marks	Solution	15	Easy
19.	Employee Names	Solution	10	Easy
20.	Employee Salaries	Solution	10	Easy

Advanced Select

S.No.	Problem	Solution	Score	Difficulty
01.	Type of Triangle	Solution	20	Easy
02.	The PADS	Solution	30	Medium
03.	Occupations	Solution	30	Medium
04.	Binary Tree Nodes	Solution	30	Medium
05.	New Companies	Solution	30	Medium

Aggregation

S.No.	Problem	Solution	Score	Difficulty
01.	Revising Aggregations - The Count Function	Solution	10	Easy
02.	Revising Aggregations - The Sum Function	Solution	10	Easy
03.	Revising Aggregations - Averages	Solution	10	Easy
04.	Average Population	Solution	10	Easy
05.	Japan Population	Solution	10	Easy
06.	Population Density Difference	Solution	10	Easy
07.	The Blunder	solution	15	Easy
08.	Top Earners	Solution	20	Easy
09.	Weather Observation Station 2	Solution	15	Easy
10.	Weather Observation Station 13	Solution	10	Easy
11.	Weather Observation Station 14	Solution	10	Easy
12.	Weather Observation Station 15	Solution	15	Easy
13.	Weather Observation Station 16	Solution	10	Easy
14.	Weather Observation Station 17	Solution	15	Easy
15.	Weather Observation Station 18	Solution	25	Medium
16.	Weather Observation Station 19	Solution	30	Medium
17.	Weather Observation Station 20	Solution	40	Medium

Basic Join

S.No.	Problem	Solution	Score	Difficulty
01.	Population Census	Solution	10	Easy
02.	African Cities	Solution	10	Easy
03.	Average Population of Each Continent	Solution	10	Easy
04.	The Report	Solution	20	Medium
05.	Top Competitors	Solution	30	Medium
06.	Ollivander's Inventory	Solution	30	Medium
07.	Challenges	Solution	30	Medium
08.	Contest Leaderboard	Solution	30	Medium

Advanced Join

S.No.	Problem	Solution	Score	Difficulty
01.	SQL Project Planning	Solution	40	Medium
02.	SQL Symmetric Pairs	Solution	40	Medium
03.	15 Days of Learning SQL	Solution	40	Medium

Alternative Queries

S.No.	Problem	Solution	Score	Difficulty
01.	Draw The Triangle 1	Solution	25	Easy
02.	Draw The Triangle 2	Solution	25	Easy

C++

Introduction

S.No.	Problem	Solution	Score	Difficulty
01.	Arrays Introduction	Solution	10	Easy
02.	Basic Data Types	Solution	10	Easy
03.	Conditional Statements	Solution	10	Easy
04.	For Loop	Solution	10	Easy
05.	Pointer	Solution	10	Easy
06.	Say "Hello, World!" With C++	Solution	05	Easy
07.	Variable Sized Arrays	Solution	30	Easy
08.	Input and Output	Solution	05	Easy

Strings

S.No.	Problem	Solution	Score	Difficulty
01.	Attribute Parser	Solution	35	Medium
02.	StringStream	Solution	10	Easy
03.	Strings	Solution	10	Easy

Classes

S.No.	Problem	Solution	Score	Difficulty
01.	Class	Solution	10	Easy
02.	Structs	Solution	10	Easy

STL

S.No.	Problem	Solution	Score	Difficulty
01.	Deque-STL	Solution	50	Medium
02.	Lower Bound-STL	Solution	15	Easy
03.	Sets-STL	Solution	15	Easy
04.	Vector-Sort	Solution	10	Easy

Inheritance

S.No.	Problem	Solution	Score	Difficulty
01.	Multi Level Inheritance	Solution	50	Medium
02.	Rectangle Area	Solution	25	Easy

Debugging

S.No.	Problem	Solution	Score	Difficulty
01.	CPP Exception Handling	Solution	20	Medium
02.	Overloading Ostream Operator	Solution	20	Medium

Other Concepts

S.No.	Problem	Solution	Score	Difficulty
01.	Operator Overloading	Solution	25	Medium

Java

Introduction

S.No.	Problem	Solution	Score	Difficulty
01.	Java Date and Time	Solution	15	Easy
02.	Java If-Else	Solution	10	Easy
03.	Java Int to String	Solution	10	Easy
04.	Java Loops II	Solution	10	Easy
05.	Java Stdin and Stdout I	Solution	05	Easy
06.	Java Stdin and Stdout II	Solution	10	Easy
07.	Welcome To Java	Solution	03	Easy

Strings

S.No.	Problem	Solution	Score	Difficulty
01.	Java Substring	Solution	05	Easy

BigNumber

S.No.	Problem	Solution	Score	Difficulty

Data Structures

S.No.	Problem	Solution	Score	Difficulty
01.	Java 1D Array	Solution	05	Easy
02.	Java Stack	Solution	20	Medium

Object Oriented Programming

S.No.	Problem	Solution	Score	Difficulty
01.	Java Abstract Class	Solution	10	Easy
02.	Java Inheritance I	Solution	05	Easy
03.	Java Inheritance II	Solution	10	Easy

Python

Introduction

S.No.	Problem	Solution	Score	Difficulty
01.	Loops	Solution	10	Easy
02.	Python Division	Solution	10	Easy
03.	Python If-Else	Solution	10	Easy
04.	Write a Function	Solution	10	Medium

Basic Data Types

S.No.	Problem	Solution	Score	Difficulty
01.	Finding the Runner-Up Score	Solution	10	Easy
02.	Finding the percentage	Solution	10	Easy
03.	List Comprehensions	Solution	10	Easy

Strings

S.No.	Problem	Solution	Score	Difficulty
01.	sWAP CASE	Solution	10	Easy