Hash

150+ posts

Meeting rooms - Find minimum meeting rooms

Last Updated: 23 July 2025

Given two arrays start[] and end[] such that start[i] is the starting time of ith meeting and end[i] is the ending time of ith meeting. Task is to find minimum number of r...read more

Last Updated: 23 July 2025

Fizz Buzz problem states that given an integer n, for every integer i = n, the task is to write a C++ program to print,'FizzBuzz' if i is divisible by 3 and 5, 'Fizz' if i...read more

2Sum - Complete Tutorial

Last Updated: 23 July 2025

The 2-Sum problem is a popular algorithmic challenge where the goal is to identify two distinct elements in an array whose sum equals a specific target. The problem emphas...read more

DSA

Hash

two-pointer-algorithm

Special Ranking Teams by Votes

Last Updated: 23 July 2025

Given an array of strings votes[], representing the voters' rankings. A special ranking system where each voter ranks all teams from highest to lowest. The task is to Sort...read more

Remove at most K letter to equalize the frequency

Last Updated: 11 June 2024

Given a string S of length n, consisting of lowercase English letters. The task is to check if it is possible to remove at most K letter from S such that the frequency of ...read more

Data Structure Design for Two Sum III

Last Updated: 27 May 2024

You have to design a data structure that accepts a stream of integers and then checks if it has a pair of integers that added/sum up to a particular value.Implement theTwo...read more

Picked

DSA

Hash

Matching the Alphanumerical Pattern in Matrix I

Last Updated: 21 May 2024

Given a 2D integer matrix mat[][] and a 2D character matrix pat[][]. Where 0 = mat[r][c] = 9 and each element of pat is either a digit or a lowercase English letter. The t...read more

Create Linked List Frequency

Last Updated: 16 May 2024

Given the head of a linked list containing k distinct elements, the task is to return the head of linked list of length k containing the frequency of each distinct element...read more

How to Implement Custom Hash Functions for User-Defined Types in std::unordered_map?

Last Updated: 23 July 2025

In C++ std::unordered_mapis a data structure that implements a hash table and allows fast access to each element based on its key. However, when we want to use user-define...read more

Count Number of Divisible Triplet Sums

Last Updated: 11 May 2024

Given a 0-indexed integer array arr[] and an integer d, return the count number of triplets (i, j, k) such that i j k and (arr[i] + arr[j] + arr[k]) % d == 0. Example:In...read more

Find Number of Same-End Substrings

Last Updated: 28 April 2024

Given a 0-indexed string s, and a 2D array of integers queries, where queries[i] = [li, ri] represents a substring of s starting from the index li and ending at the index ...read more

CSES Solution - Palindrome Queries

Last Updated: 28 March 2024

You are given a string that consists of n characters between a–z. The positions of the string are indexed 1,2,...n.Your task is to process m operations of the following ty...read more

Competitive Programming

Picked

Hash

CSES Problems

Transform Strings by Frequency Exchange and Swapping

Last Updated: 23 July 2025

Given two strings s1 and s2, the task is to check if they can be transformed into each other by performing the following operation any number of times on any string.Choosi...read more

Geeks Premier League 2023

Rearrange arrays such that sum of corresponding elements is same for all equal indices

Last Updated: 28 January 2024

Given two arrays A[] and B[] of length N. Then your task is to rearrange the elements of both arrays in such a way that the sum (Ai + Bi) for all i (1 = i = N) is same. If...read more

Geeks Premier League 2023

Find sum of count of duplicate numbers in all subarrays of given array

Last Updated: 15 February 2024

Given an array arr[] of size N. The task it to find the sum of count of duplicate numbers in all subarrays of given array arr[]. For example array {1, 2, 3, 2, 3, 2} has t...read more

Geeks Premier League 2023

1 2 3 4

...