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DSA

20.2K+ posts

Last Updated: 08 August 2025

Given an array arr[] of positive integers and an integer k. Find the sum of the modes of all subarrays of size k.Note: The mode of a subarray is the element that occurs wi...read more

DSA

Understanding Prefix Sums

Last Updated: 28 July 2025

In programming, prefix sum arrays are a simple and powerful technique. They make it easier to solve problems that involve finding the sum of numbers between two points in ...read more

DSA

Count Target in Sorted Matrix

Last Updated: 06 August 2025

Given a 2D matrix mat[][] and an integer x, count the number of times x appears in the matrix.The matrix follows these sorting rules:Each row is sorted in increasing order...read more

DSA

Range-Based Count of X in Sorted Array

Last Updated: 01 August 2025

Given a sorted array arr[] and a list of queries represented as a 2D array queries[][]. Each query is a triplet of the form [l, r, x], where l and r are indices in the arr...read more

DSA

Count Elements in Range Queries

Last Updated: 07 August 2025

Given an unsorted array arr[] and a 2D array of queries[][], where each query is in the form of [a, b]. For each query, count how many elements in arr[] lie within the ran...read more

DSA

Count Frequency of an Element in a Given Range

Last Updated: 16 July 2025

Given an array arr[] of integers and a 2D array queries[][], where each queries[i] contains three integers: l, r, and x. For each query, determine how many times the eleme...read more

DSA

Binary Search

Maximum Non-Overlapping Odd Palindrome Sum

Last Updated: 31 July 2025

Given a string s consisting of lowercase English letters, find the maximum possible sum of the lengths of any two non-empty and non-overlapping palindromic substrings of o...read more

DSA

strings

Tywin's War Strategy

Last Updated: 18 July 2025

Given an array arr[] of length n, where arr[i] is the number of soldiers in the i-th troop, and an integer k. A troop is called lucky if its soldier count is a multiple of...read more

DSA

Minimize Difference

Last Updated: 24 July 2025

Given an array arr[] of strings, where each string represents a time in 24-hour format ("HH:MM:SS"), find the minimum absolute difference in seconds between any two time v...read more

DSA

strings

Longest Periodic Proper Prefix

Last Updated: 04 August 2025

Given a string s, find the length of the longest proper prefix such that repeating this prefix one or more times forms a string that contains s as a prefix. If no such pre...read more

DSA

Balance Consonant and Vowels Ratio

Last Updated: 11 July 2025

You are given an array of strings arr[], where each string contains only lowercase English letters. Count the number of contiguous subarrays (i.e., one or more consecutive...read more

DSA

Powerful Integers

Last Updated: 05 July 2025

You are given a 2D integer array intervals[][] of length n and integer k, where each intervals[i] = [start, end] represents a closed interval (i.e., all integers from star...read more

Last Updated: 28 July 2025

Given a string s consisting of lowercase English letters, identify all characters whose first and last occurrences are at different positions.For each such character, comp...read more

Local Min and Max Sequence Ordering

Last Updated: 23 July 2025

Given an integer array arr[] representing a sequence of elevations, Return an array that includes:The first and last elements of the array.Every element where the trend of...read more

DSA

Counting Even-Frequency Characters in a String

Last Updated: 26 July 2025

Given a string s consist of lowercase english letters, count how many distinct characters appear an even number of times.Examples: Input: s = "abacaba"Output: 2Explanation...read more

DSA

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