Practice Arena
Problems
Practice coding problems by topic and difficulty with JS-only in-browser runner.
277 curated problems JS runner enabled Local progress tracking
277 problems
Easy Array Not Solved
Easy Array Not Solved
Sort Colors
Easy Array Not Solved
Majority Element
Easy Array Not Solved
Remove Duplicates from Sorted Array
Easy Array Not Solved
Set Matrix Zeroes
Easy Array Not Solved
Move Zeroes
Easy Array Not Solved
Best Time to Buy and Sell Stock
Easy Array Not Solved
Chocolate Distribution Problem
Easy Array Not Solved
Two Sum
Easy Array Not Solved
Best Time to Buy and Sell Stock II
Easy Array Not Solved
Merge Sorted Array
Medium Array Not Solved
Subarray Sum Equals K
Medium Array Not Solved
Subarray Sums Divisible by K
Medium Array Not Solved
Find All Duplicates in an Array
Medium Array Not Solved
Container With Most Water
Medium Array Not Solved
3Sum
Medium Array Not Solved
3Sum Closest
Medium Array Not Solved
4Sum
Medium Array Not Solved
Maximum Points You Can Obtain from Cards
Medium Array Not Solved
Spiral Matrix
Medium Array Not Solved
Word Search
Medium Array Not Solved
Jump Game
Medium Array Not Solved
Print all combinations | Set-2
Medium Array Not Solved
Game of Life
Hard Array Not Solved
Reverse Pairs
Hard Array Not Solved
Insert Delete GetRandom O(1) - Duplicates allowed
Hard Array Not Solved
Largest Rectangle in Histogram
Hard Array Not Solved
Max Value of Equation
Easy String Not Solved
Valid Parentheses
Easy String Not Solved
Print all the duplicate characters in a string
Easy String Not Solved
Find the Index of the First Occurrence in a String
Easy String Not Solved
Longest Common Prefix
Easy String Not Solved
Valid Palindrome II
Medium String Not Solved
Integer to Roman
Medium String Not Solved
Generate Parentheses
Medium String Not Solved
Simplify Path
Medium String Not Solved
Smallest window containing all characters of another string | Practice
Medium String Not Solved
Reverse Words in a String
Medium String Not Solved
Rabin-Karp Algorithm for Pattern Searching
Medium String Not Solved
Group Anagrams
Medium String Not Solved
Word Wrap | Practice
Medium String Not Solved
Basic Calculator II
Hard String Not Solved
Valid Number
Hard String Not Solved
Integer to English Words
Hard String Not Solved
Minimum Window Substring
Hard String Not Solved
Text Justification
Hard String Not Solved
Boyer Moore Algorithm for Pattern Searching
Hard String Not Solved
Distinct Subsequences
Medium Matrix Not Solved
Maximum size rectangle binary sub-matrix with all 1s
Medium Matrix Not Solved
Number of Islands
Medium Matrix Not Solved
Given a matrix of ‘O’ and ‘X’, replace ‘O’ with ‘X’ if surrounded by ‘X’
Medium Matrix Not Solved
Spiral Matrix
Medium Matrix Not Solved
Rotate Image
Easy Matrix Not Solved
Minimum Moves to Equal Array Elements
Easy Matrix Not Solved
Add Binary
Easy Matrix Not Solved
Maximum Product of Three Numbers
Easy Matrix Not Solved
Excel Sheet Column Title
Easy Matrix Not Solved
Happy Number
Easy Matrix Not Solved
Palindrome Number
Easy Matrix Not Solved
Missing Number
Easy Matrix Not Solved
Reverse Integer
Easy Matrix Not Solved
Power of Two
Medium Matrix Not Solved
Max Points on a Line
Medium Matrix Not Solved
Valid Square
Medium Matrix Not Solved
The kth Factor of n
Easy Sorting&Searching Not Solved
Permute two arrays such that sum of every pair is greater or equal to K
Easy Sorting&Searching Not Solved
Ceiling in a sorted array
Easy Sorting&Searching Not Solved
Pair with the given difference
Easy Sorting&Searching Not Solved
Permute two arrays such that sum of every pair is greater or equal to K
Medium Sorting&Searching Not Solved
Check if reversing a sub array make the array sorted
Medium Sorting&Searching Not Solved
Radix Sort – Data Structures and Algorithms Tutorials
Medium Sorting&Searching Not Solved
Product of Array Except Self
Medium Sorting&Searching Not Solved
Make all array elements equal with minimum cost
Medium Sorting&Searching Not Solved
Find Peak Element
Hard Sorting&Searching Not Solved
Allocate Minimum Pages | Practice
Hard Sorting&Searching Not Solved
Minimum swaps to sort an array
Hard Sorting&Searching Not Solved
SPOJ.com - Problem AGGRCOW
Hard Sorting&Searching Not Solved
Search in Rotated Sorted Array
Hard Sorting&Searching Not Solved
Count of Smaller Numbers After Self
Hard Sorting&Searching Not Solved
Split Array Largest Sum
Easy Linked-List Not Solved
Middle of the Linked List
Easy Linked-List Not Solved
Linked List Cycle
Easy Linked-List Not Solved
Convert Binary Number in a Linked List to Integer
Easy Linked-List Not Solved
Remove Duplicates from Sorted List
Easy Linked-List Not Solved
Sort a linked list of 0s, 1s and 2s
Easy Linked-List Not Solved
Remove Linked List Elements
Easy Linked-List Not Solved
Merge Two Sorted Lists
Easy Linked-List Not Solved
Multiply two numbers represented by Linked Lists
Easy Linked-List Not Solved
Intersection of Two Linked Lists
Easy Linked-List Not Solved
Given only a pointer/reference to a node to be deleted in a singly linked list, how do you delete it?
Easy Linked-List Not Solved
Palindrome Linked List
Easy Linked-List Not Solved
Reverse Linked List
Medium Linked-List Not Solved
Add Two Numbers
Medium Linked-List Not Solved
Copy List with Random Pointer
Medium Linked-List Not Solved
Add Two Numbers II
Medium Linked-List Not Solved
Reverse Linked List II
Medium Linked-List Not Solved
Reorder List
Medium Linked-List Not Solved
Remove Nth Node From End of List
Medium Linked-List Not Solved
Flatten a Multilevel Doubly Linked List
Medium Linked-List Not Solved
Partition List
Medium Linked-List Not Solved
Remove Duplicates from Sorted List II
Medium Linked-List Not Solved
Rearrange a Linked List in Zig-Zag fashion
Medium Linked-List Not Solved
Sort List
Medium Linked-List Not Solved
Segregate even and odd nodes in a Linked List
Medium Linked-List Not Solved
Rearrange a given linked list in-place
Hard Linked-List Not Solved
Merge k Sorted Lists
Hard Linked-List Not Solved
Reverse Nodes in k-Group
Hard Linked-List Not Solved
Merge Sort for Linked Lists
Hard Linked-List Not Solved
Flattening a Linked List
Hard Linked-List Not Solved
Subtract Two Numbers represented as Linked Lists
Easy Stack&Queue Not Solved
Implement Queue using Stacks
Easy Stack&Queue Not Solved
Backspace String Compare
Easy Stack&Queue Not Solved
Implement Stack using Queues
Easy Stack&Queue Not Solved
Implement Stack and Queue using Deque
Easy Stack&Queue Not Solved
Next Greater Element I
Easy Stack&Queue Not Solved
Evaluation of Postfix Expression
Easy Stack&Queue Not Solved
Implement two Stacks in an Array
Medium Stack&Queue Not Solved
Letter Combinations of a Phone Number
Medium Stack&Queue Not Solved
Minimum Cost Tree From Leaf Values
Medium Stack&Queue Not Solved
Daily Temperatures
Medium Stack&Queue Not Solved
Distance of nearest cell having 1 | Practice
Medium Stack&Queue Not Solved
Online Stock Span
Medium Stack&Queue Not Solved
Rotten Oranges | Practice
Medium Stack&Queue Not Solved
Sum of Subarray Minimums
Medium Stack&Queue Not Solved
Evaluate Reverse Polish Notation
Medium Stack&Queue Not Solved
Gas Station | Practice
Medium Stack&Queue Not Solved
https://leetcode.com/problems/implement-stack-using-queues
Medium Stack&Queue Not Solved
Flatten Nested List Iterator
Hard Stack&Queue Not Solved
Maximum of minimums of every window size in a given array
Hard Stack&Queue Not Solved
LRU Cache – Complete Tutorial
Hard Stack&Queue Not Solved
The Celebrity Problem
Easy Tree Not Solved
Diameter of Binary Tree
Easy Tree Not Solved
Invert Binary Tree
Easy Tree Not Solved
Subtree of Another Tree
Easy Tree Not Solved
Range Sum of BST
Easy Tree Not Solved
Symmetric Tree
Easy Tree Not Solved
Convert Sorted Array to Binary Search Tree
Easy Tree Not Solved
Merge Two Binary Trees
Easy Tree Not Solved
Maximum Depth of Binary Tree
Easy Tree Not Solved
Binary Tree Paths
Easy Tree Not Solved
Same Tree
Easy Tree Not Solved
Lowest Common Ancestor of a Binary Search Tree
Easy Tree Not Solved
Path Sum
Easy Tree Not Solved
Minimum Absolute Difference in BST
Easy Tree Not Solved
Sum of Left Leaves
Easy Tree Not Solved
Balanced Binary Tree
Easy Tree Not Solved
Predecessor and Successor | Practice
Easy Tree Not Solved
https://leetcode.com/problems/binary-tree-inorder-traversal/
Easy Tree Not Solved
BST with Dead End | Practice
Medium Tree Not Solved
Binary Search Tree Iterator
Medium Tree Not Solved
Lowest Common Ancestor of a Binary Tree
Medium Tree Not Solved
Unique Binary Search Trees II
Medium Tree Not Solved
All Nodes Distance K in Binary Tree
Medium Tree Not Solved
Validate Binary Search Tree
Medium Tree Not Solved
Binary Tree Right Side View
Medium Tree Not Solved
Redundant Connection
Medium Tree Not Solved
Binary Tree Level Order Traversal
Medium Tree Not Solved
Path Sum III
Medium Tree Not Solved
Construct Binary Tree from Preorder and Postorder Traversal
Medium Tree Not Solved
Unique Binary Search Trees
Medium Tree Not Solved
Recover Binary Search Tree
Medium Tree Not Solved
Populating Next Right Pointers in Each Node
Medium Tree Not Solved
Flatten Binary Tree to Linked List
Medium Tree Not Solved
Maximum Width of Binary Tree
Medium Tree Not Solved
Min distance between two given nodes of a Binary Tree | Practice
Medium Tree Not Solved
Kth Smallest Element in a BST
Medium Tree Not Solved
Binary Tree Zigzag Level Order Traversal
Medium Tree Not Solved
Count BST nodes that lie in a given range | Practice
Medium Tree Not Solved
Preorder to BST | Practice
Hard Tree Not Solved
https://practice.geeksforgeeks.org/problems/binary-tree-to-dll/1
Hard Tree Not Solved
Binary Tree Maximum Path Sum
Hard Tree Not Solved
Sum of Distances in Tree
Hard Tree Not Solved
Binary Tree Cameras
Hard Tree Not Solved
Vertical Order Traversal of a Binary Tree
Hard Tree Not Solved
Print all k-sum paths in a binary tree
Hard Tree Not Solved
Serialize and Deserialize Binary Tree
Hard Tree Not Solved
Find median of BST
Hard Tree Not Solved
Largest BST in a Binary Tree
Hard Tree Not Solved
Construct BST from Preorder Traversal
Easy Graph Not Solved
BFS of graph | Practice
Easy Graph Not Solved
Depth First Search or DFS for a Graph
Easy Graph Not Solved
Number of Islands
Easy Graph Not Solved
Flood Fill
Easy Graph Not Solved
Rat in a Maze Problem - I | Practice
Easy Graph Not Solved
Undirected Graph Cycle | Practice
Easy Graph Not Solved
Detect Cycle in a Directed Graph
Medium Graph Not Solved
Steps by Knight | Practice
Medium Graph Not Solved
Decode String
Medium Graph Not Solved
Shortest Bridge
Medium Graph Not Solved
Number of Operations to Make Network Connected
Medium Graph Not Solved
Find Eventual Safe States
Medium Graph Not Solved
Strongly Connected | Practice
Medium Graph Not Solved
Time Needed to Inform All Employees
Medium Graph Not Solved
Introduction to Graph Coloring
Medium Graph Not Solved
Most Stones Removed with Same Row or Column
Medium Graph Not Solved
As Far from Land as Possible
Medium Graph Not Solved
Find the City With the Smallest Number of Neighbors at a Threshold Distance
Medium Graph Not Solved
Check if it is possible to finish all task from given dependencies (Course Schedule I)
Medium Graph Not Solved
Prim’s Algorithm for Minimum Spanning Tree (MST)
Medium Graph Not Solved
Floyd Warshall | Practice
Medium Graph Not Solved
Evaluate Division
Medium Graph Not Solved
Snakes and Ladders
Medium Graph Not Solved
Topological sort | Practice
Medium Graph Not Solved
Cheapest Flights Within K Stops
Medium Graph Not Solved
Detect a negative cycle in a Graph | (Bellman Ford)
Medium Graph Not Solved
Check whether a given graph is Bipartite or not
Hard Graph Not Solved
Longest Increasing Path in a Matrix
Hard Graph Not Solved
Making A Large Island
Hard Graph Not Solved
Remove Boxes
Hard Graph Not Solved
Critical Connections in a Network
Hard Graph Not Solved
alien-dictionary
Hard Graph Not Solved
Water Jug problem using BFS
Hard Graph Not Solved
Travelling Salesman Problem using Dynamic Programming
Hard Graph Not Solved
Total number of Spanning Trees in a Graph
Hard Graph Not Solved
Word Ladder
Hard Graph Not Solved
Minimize Cash Flow among a given set of friends who have borrowed money from each other
Medium Tries Not Solved
Design Add and Search Words Data Structure
Medium Tries Not Solved
Word Break Problem | (Trie solution)
Medium Tries Not Solved
Trie Data Structure
Medium Tries Not Solved
Print Anagrams Together | Practice
Hard Tries Not Solved
Palindrome Pairs
Hard Tries Not Solved
phone-directory
Hard Heap Not Solved
Minimum Number of Refueling Stops
Hard Heap Not Solved
Minimum Cost to Hire K Workers
Hard Heap Not Solved
Swim in Rising Water
Hard Heap Not Solved
Sliding Window Maximum
Easy Dynamic-Programming Not Solved
Climbing Stairs
Easy Dynamic-Programming Not Solved
Maximum Product Subarray
Easy Dynamic-Programming Not Solved
Ones and Zeroes
Easy Dynamic-Programming Not Solved
Counting Bits
Medium Dynamic-Programming Not Solved
Knight Dialer
Medium Dynamic-Programming Not Solved
Maximize The Cut Segments | Practice
Medium Dynamic-Programming Not Solved
Unique Paths
Medium Dynamic-Programming Not Solved
Minimum Path Sum
Medium Dynamic-Programming Not Solved
Coin Change
Medium Dynamic-Programming Not Solved
Decode Ways
Medium Dynamic-Programming Not Solved
Maximum Length of Repeated Subarray
Medium Dynamic-Programming Not Solved
Longest Increasing Subsequence
Medium Dynamic-Programming Not Solved
Longest Common Substring | Practice
Medium Dynamic-Programming Not Solved
Count Square Submatrices with All Ones
Medium Dynamic-Programming Not Solved
Maximal Square
Medium Dynamic-Programming Not Solved
Mobile numeric keypad | Practice
Medium Dynamic-Programming Not Solved
Weighted Job Scheduling
Medium Dynamic-Programming Not Solved
Delete and Earn
Medium Dynamic-Programming Not Solved
Range Sum Query 2D - Immutable
Hard Dynamic-Programming Not Solved
Optimal Binary Search Tree
Hard Dynamic-Programming Not Solved
Frog Jump
Hard Dynamic-Programming Not Solved
Best Time to Buy and Sell Stock IV
Hard Dynamic-Programming Not Solved
Minimum Insertion Steps to Make a String Palindrome
Hard Dynamic-Programming Not Solved
Largest area rectangular sub-matrix with equal number of 1’s and 0’s
Hard Dynamic-Programming Not Solved
Trapping Rain Water
Hard Dynamic-Programming Not Solved
Minimum Cost to Merge Stones
Hard Dynamic-Programming Not Solved
Count Different Palindromic Subsequences
Hard Dynamic-Programming Not Solved
Maximal Rectangle
Hard Dynamic-Programming Not Solved
Burst Balloons
Hard Dynamic-Programming Not Solved
Super Egg Drop
Medium Two-Pointer Not Solved
Sort Colors
Medium Two-Pointer Not Solved
Longest Repeating Character Replacement
Medium Two-Pointer Not Solved
Maximum Number of Visible Points
Medium Backtracking Not Solved
Combination Sum II
Medium Backtracking Not Solved
https://practice.geeksforgeeks.org/problems/subset-sum-problem2014/1
Medium Backtracking Not Solved
Combinations
Medium Backtracking Not Solved
Subsets II
Medium Backtracking Not Solved
M-Coloring Problem | Practice
Medium Backtracking Not Solved
Beautiful Arrangement
Medium Backtracking Not Solved
Palindrome Partitioning
Medium Backtracking Not Solved
Permutations II
Hard Backtracking Not Solved
https://leetcode.com/problems/word-search-ii/
Hard Backtracking Not Solved
Sudoku Solver
Hard Backtracking Not Solved
N-Queens
Hard Backtracking Not Solved
Unique Paths III
Hard Backtracking Not Solved
Find Maximum number possible by doing at-most K swaps
Hard Backtracking Not Solved
Partition of a set into K subsets with equal sum
Hard Backtracking Not Solved
Tug of War
Hard Backtracking Not Solved
Find paths from corner cell to middle cell in maze
Hard Backtracking Not Solved
Solving Cryptarithmetic Puzzles
Hard Backtracking Not Solved
Print all Palindromic Partitions of a String using Bit Manipulation
Solved
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