Problems

All coding problems organized by difficulty.

Showing 137 of 137

Easy (32)

All divisors of a number

Maths

Check For Prime

Maths

Check if a String is a Subsequence of Another String

Strings, Two Pointers, Greedy

Check if the K-th Bit is Set or Not

Maths

If number is power of 2

Maths

Chocolate Distribution Problem

Arrays, Sorting, Sliding Window...

Count Digits

Maths

Count Distinct Elements in Every Window

Arrays, Hashing, Sliding Window

Equilibrium Point

Arrays, Prefix Sum

Find All Anagrams in a String (Leetcode 438)

Strings, Hashing, Sliding Window

First Occurrence Last Occurrence & Count in a Sorted Array

Arrays, Searching

Greatest Common Divisor

Maths

Implement Queue using Stacks (LeetCode 232)

Stack, Queue

Implement Two Stacks in One Array

Stack, Arrays

Least Common Multiple

Maths

Leftmost Non-Repeating Character (Leetcode 387)

Strings, Hashing

Longest Consecutive Subsequence (Leetcode 128)

Arrays, Hashing, Greedy

Majority Element

Arrays

Maximum sum of K consecutive elements

Arrays, Sliding Window

Leetcode 1710 — Maximum Units on a Truck

Greedy, Sorting

Minimum Consecutive Flips

Arrays

Pair With Given Sum in an Unsorted Array

Arrays, Hashing

Prime Factors

Maths

Reverse Words in a String (Leetcode 151)

Strings, Two Pointers

Search in an Infinite Sorted Array

Searching

Square root using binary search

Searching

Stack using Queue (LeetCode 225)

Stack, Queue

Top K Frequent Elements (Leetcode 347)

Arrays, Hashing, Heap...

Two Sum (Leetcode 1)

Two Pointers, Arrays

Valid Anagram (leetcode 242)

Arrays, Hashing, Strings

Valid Parentheses (Leetcode 20)

Stack, Strings

Weighted Sum range queries

Arrays, Prefix Sum

Medium (54)

3Sum

Two Pointers, Arrays

Binary Exponentiation

Maths

Check if Two Strings are Rotations of Each Other (Leetcode 796)

Strings

Count set bits

Maths

Count Subarrays with Given Sum

Arrays, Prefix Sum, Hashing

Counting Distinct Rows in a Binary Matrix

Strings, Matrix, Hashing...

Elements Occurring More Than n/k Times

Arrays, Hashing, Sorting...

Equal Partition

DP

Find All Duplicates in an Array (LC 442)

Arrays

Find duplicate number (LC-287)

Arrays, Two Pointers, Linked Lists

Find Minimum Element in a Sorted Rotated Array

Arrays, Searching

Find peak in mountain array

Arrays, Searching

Find the Smallest Divisor Given a Threshold

Searching

Gas Station (Leetcode 134)

Arrays, Greedy, Prefix Sum

Group Anagrams (Leetcode 49)

Arrays, Strings, Sorting...

Implementation of Deque using Circular Array (Leetcode 641)

Queue, Arrays

Intersection of Two Sorted Arrays

Arrays, Sorting

Job Sequencing Problem with Deadlines

Arrays, Greedy, Sorting...

Kth smallest element in an array

Sorting, Heap, Arrays

Largest Number (Leetcode 179)

Strings, Greedy, Sorting

Leftmost Repeating Character

Strings, Hashing

Longest Palindromic Substring (leetcode 5)

Strings, Two Pointers

Longest Subarray with Equal Number of 0s and 1s

Arrays, Prefix Sum, Hashing

Longest Substring Without Repeating Characters (leetcode 3)

Sliding Window, Strings, Hashing

Magnetic Force Between Two Balls / Aggressive Cows

Searching, Greedy

Maximum Candies Allocated to K Children (LC 2226)

Searching

Maximize Points You Can Get from Cards (Leetcode 1423)

Arrays, Sliding Window

Maximum Subarray Sum

Arrays

Min Stack (Leetcode 155)

Stack

Minimized Maximum of Products Distributed to Any Store

Searching

Minimum Limit of Balls in a Bag

Searching

Minimum Number of Steps to Make Two Strings Anagram (LC 1347)

Strings, Hashing

Minimum Number of Steps to Make Two Strings Anagram II (leetcode 2186)

Strings, Hashing

Next Greater Element (NGE)

Stack, Arrays, Greedy

Odd one occurring

Maths

Palindrome number

Maths

Permutations 2 (handling duplicates)

Maths, Backtracking

Power Set using Bitwise

Maths

Previous Greater Element (PGE)

Stack, Arrays, Greedy

Print First N Numbers Formed Using a Given Digit Set

Queue, Maths

Remove Duplicate Letters / Smallest Subsequence of Distinct Characters (Leetcode 316 / 1081)

Strings, Greedy, Hashing...

Repeated Substring Pattern (Leetcode 459)

Strings

Rope Cutting With DP

Recursion, DP

Rotate Matrix by 90° Anti-Clockwise

Matrix

Search in Sorted Rotated Array (Distinct Elements)

Arrays, Searching

Sieve Of Eratosthenes

Maths

Stock Span Problem (Leetcode 901)

Stack, Arrays, Greedy

Subarray with given sum

Arrays, Sliding Window, Prefix Sum...

Subset sum using DP

DP

Top K closest Elements (leetcode 658)

Arrays, Searching, Two Pointers...

Tower Of Hanoi

Recursion

Trailing zeroes in a factorial

Maths

Transpose of a Matrix

Matrix

Union of Two Sorted Arrays

Sorting, Arrays

Hard (48)

Capacity to Ship Packages Within D Days

Searching, Greedy

Count Inversions in Array

Arrays, Sorting

Count Subsets with Given Sum

DP

Divide Chocolate (Leetcode 1231)

Searching, Greedy

Find a peak element in 2D matrix

Arrays, Searching, Matrix

Find K Pairs With Smallest Sums

Heap, Two Pointers

Find Peak Element

Arrays, Searching

First Missing Positive (LC 41)

Arrays, Sorting, Hashing

Infix to Postfix (Shunting Yard Algorithm)

Stack

Infix to Prefix (Shunting Yard Variant)

Stack

Josephus Problem

Recursion

Koko Eating Bananas - Predicate Search

Searching

Kth element in two sorted arrays

Arrays, Searching, Two Pointers

Kth Smallest Element in a Sorted Matrix

Heap, Matrix, Searching

K-th Smallest Number in Multiplication Table

Searching

Kth smallest pair distance

Searching, Two Pointers

Largest Rectangle in Histogram (leetcode 84)

Arrays, Stack

Lexicographic Rank of a String

Strings, Combinatorics

Longest Common Span with Same Sum in Binary Arrays

Arrays, Prefix Sum, Hashing

Longest Duplicate Substring (Leetcode 1044)

Strings, Searching, Hashing

Longest Subarray With Given Sum

Arrays, Prefix Sum, Hashing...

Maximal Rectangle (Leetcode 85) (largest rectangle with all 1's)

Matrix, Stack

Maximum Appearing Element

Arrays, Difference Array

Maximum Contiguous Subarray Sum ≤ K

Arrays, Prefix Sum, Ordered Containers

Max Sum of Rectangle No Larger Than K (Leetcode 363)

Matrix, Prefix Sum, Ordered Containers

Maximum Sum Rectangle in a 2D Matrix (Kadane's 2D)

Arrays, Greedy, Matrix

Median in a Row-wise Sorted Matrix

Matrix

Median of Two Sorted Arrays

Arrays, Searching, Two Pointers

Merge K Sorted Lists — K-Way Merge

Linked Lists, Heap

Minimize Max Distance to Gas Station

Searching, Greedy

Minimum Number of Operations to Make String Sorted (Leetcode 1830)

Maths, Combinatorics, Strings...

Minimum Operations to Reduce X to Zero (Leetcode 1658)

Arrays, Sliding Window

N-Queens (Leetcode 51 & 52)

Backtracking, Maths, Recursion...

Next Permutation (Leetcode 31)

Arrays, Greedy, Two Pointers

Postfix to Infix & Evaluation of Postfix (Leetcode 150)

Stack

Power Set with Duplicates

Maths, Sorting, Backtracking

Prefix to Infix & Evaluation of Prefix

Stack

Repeating Element (Cycle + Expected Sum appr.)

Arrays, Two Pointers, Linked Lists

Search in Rotated Sorted Array II (With Duplicates)

Arrays, Searching

Shortest Palindrome (Leetcode 214)

Strings, Greedy

Sliding Window Maximum (Leetcode 239)

Arrays, Prefix Sum, Sliding Window...

Sliding Window Maximum (Leetcode 239)

Arrays, Sliding Window, Queue

Smallest Range Covering Elements from K Sorted Lists

Heap

Spiral Traversal of a Matrix

Matrix

Split Array Largest Sum

Searching, Greedy

Subarray Sum Divisible by K

Arrays, Prefix Sum, Hashing

Trapping Rain Water (LC 42)

Two Pointers, Prefix and Suffix Arrays, Stack

Two odd occurring

Maths

Not Specified (3)

Best Time to Buy and Sell Stock

Arrays, DP

Container With Most Water

Two Pointers

Contains Duplicate

Arrays, Hashing