AlgoMaster DSA Animations

Bubble Sort

Sort an array using the bubble sort algorithm

Selection Sort

Sort an array using the selection sort algorithm

Insertion Sort

Sort an array using the insertion sort algorithm

Merge Sort (Iterative)

Sort an array using the bottom-up iterative merge sort algorithm

Array

Move Zeroes

Move all zeroes to end while maintaining relative order

Majority Element

Find the majority element in an array

Remove Duplicates from Sorted Array

Remove duplicates from a sorted array

Best Time to Buy and Sell Stock

Find maximum profit from single buy and sell transaction

Rotate Array

Rotate an array by k steps

Product of Array Except Self

Calculate product of array except self

Best Time to Buy and Sell Stock II

Find maximum profit from multiple buy and sell transactions

Number of Zero-Filled Subarrays

Find number of zero-filled subarrays

Increasing Triplet Subsequence

Find increasing triplet subsequence

First Missing Positive

Find the first missing positive integer in an array

String

Is Subsequence

Check if s is a subsequence of t

Valid Palindrome

Check if a string is a valid palindrome

Longest Common Prefix

Find the longest common prefix in an array of strings

Reverse Words in a String

Reverse the words in a string

Bit Manipulation

Single Number

Find the single number in an array where every other number appears twice

Counting Bits

Count the number of 1 bits in the binary representation of a number

Single Number III

Find the two numbers in an array where every other number appears twice

Hash Table

Ransom Note

Check if a ransom note can be constructed from a magazine

Number of Good Pairs

Find the number of good pairs in an array

Maximum Number of Balloons

Find the maximum number of balloons in a string

Contains Duplicate II

Check if an array contains duplicate elements within k distance

Isomorphic Strings

Check if two strings are isomorphic

Group Anagrams

Group anagrams together

Reorganize String

Reorganize a string so that no two adjacent characters are the same

Longest Consecutive Sequence

Find the longest consecutive sequence in an array

Number of Good Ways to Split a String

Find the number of good ways to split a string

Two Pointers

Merge Sorted Array

Merge two sorted arrays into a single sorted array

Two Sum II - Input Array Is Sorted

Find two numbers that add up to target using two pointers on sorted array

Container with Most Water

Find two lines that form a container with maximum water capacity

3Sum

Find all unique triplets that sum to zero

Trapping Rain Water

Calculate total water trapped between elevation bars after raining

Prefix Sum

Contiguous Array

Find longest subarray with equal number of 0s and 1s using hash map

Continuous Subarray Sum

Check if array has subarray (size ≥ 2) with sum that is multiple of k

Subarray Sum Equals K

Find subarrays with sum equal to target using prefix sums

Subarray Sum Divisible by K

Find subarrays with sum divisible by k using prefix sums

Sliding Window

Maximum Average Subarray I

Find maximum average of contiguous subarray of length k using sliding window

Permutation in String

Check if s1 is a permutation of s2 using sliding window

Find All Anagrams in a String

Find all anagrams of s1 in s2 using sliding window

Minimum Size Subarray Sum

Find minimal length subarray with sum ≥ target using variable-size sliding window

Max Consecutive Ones III

Find max consecutive 1s after flipping at most k zeros using sliding window

Longest Substring Without Repeating Characters

Find the length of the longest substring without repeating characters

Minimum Window Substring

Find the minimum window in string that contains all characters of target

Kadane's Algorithm

Maximum Subarray

Find the contiguous subarray with the largest sum (Kadane's Algorithm)

Maximum Product Subarray

Find the contiguous subarray with the largest product (Kadane's Algorithm)

Best Sightseeing Pair

Find the best sightseeing pair in an array

Matrix

Spiral Matrix

Traverse matrix in spiral order from outer to inner layers

Rotate Image

Rotate n×n matrix 90 degrees clockwise using transpose then reverse

Set Matrix Zeroes

Set entire row and column to zero if element is zero using O(1) space

Linked List

Middle of the Linked List

Find the middle node of a linked list

Remove Nth Node From End of List

Remove the nth node from the end of a linked list

Reverse Linked List

Reverse a singly linked list using three pointers

Reverse Linked List II

Reverse a sublist from position left to right in one pass

Reverse Nodes in k-Group

Reverse nodes in k-sized groups using iterative in-place reversal

Remove Duplicates from Sorted List II

Remove all nodes with duplicate values from a sorted linked list

Merge Two Sorted Lists

Merge two sorted linked lists into a single sorted linked list

Linked List Cycle II

Detect cycle and find entry point using Floyd's algorithm

Swap Nodes in Pairs

Swap every two adjacent nodes in a linked list

Partition List

Partition a linked list around a value x

Rotate List

Rotate a linked list to the right by k places

Add Two Numbers

Add two numbers represented by linked lists

Copy List with Random Pointer

Deep copy a linked list with random pointers using three-pass interleaving

Flatten a Multilevel Doubly Linked List

Flatten a multilevel doubly linked list by inserting child lists inline

Intersection of Two Linked Lists

Find the node where two linked lists intersect using two pointers

Stack

Valid Parentheses

Determine if a string of brackets is properly balanced using a stack

Remove All Adjacent Duplicates In String

Remove all adjacent duplicates in a string using a stack

Remove Duplicate Letters

Remove duplicate letters from a string to form the lexicographically smallest string

Removing Stars From a String

Remove stars from a string

Evaluate Reverse Polish Notation

Evaluate a reverse polish notation expression using a stack

Basic Calculator II

Evaluate a basic calculator expression using a stack

Longest Valid Parentheses

Find the longest valid parentheses substring using a stack

Next Greater Element I

Find the next greater element for each element in nums1 using a stack

Daily Temperatures

Find how many days until a warmer temperature using monotonic stack

132 Pattern

Find the 132 pattern in an array using a stack

Number of Visible People in a Queue

Find the number of visible people in a queue using a stack

Largest Rectangle in Histogram

Find the largest rectangle area in a histogram using a monotonic stack

Queue

Reveal Cards In Increasing Order

Arrange deck so cards are revealed in increasing order using queue simulation

Jump Game VI

Find the maximum score of a jump game using a queue

Sliding Window Maximum

Find maximum in each sliding window using monotonic deque

Max Value of Equation

Find the maximum value of equation using a queue

QuickSelect

Sort Colors

Sort an array of 0s, 1s, and 2s using the quickselect algorithm

Heaps

Kth Largest Element in an Array

Find the kth largest element in an array using a min-heap

Binary Search

Search Insert Position

Find the insertion position of a target in a sorted array using binary search

Search in Rotated Sorted Array

Find target in rotated sorted array using modified binary search

Find Peak Element

Find the peak element in a sorted array using binary search

Find Minimum in Rotated Sorted Array

Find the minimum element in a rotated sorted array using binary search

Search in 2D Matrix

Find target in sorted 2D matrix using binary search

Backtracking

Subsets

Generate all subsets using recursive backtracking with decision tree

Permutations

Generate all permutations by choosing unused elements recursively

Tree

Binary Tree Level Order Traversal

Traverse tree level by level using BFS and queue

Binary Tree Right Side View

Traverse tree right side view using BFS and queue

Binary Tree Zigzag Level Order Traversal

Traverse tree level by level in zigzag pattern using BFS and queue

Populating Next Right Pointers in Each Node II

Connect nodes at same level using BFS with queue

Binary Tree Preorder Traversal

Traverse tree preorder using DFS and stack

Same Tree

Check if two binary trees are identical

Symmetric Tree

Check if a binary tree is symmetric

Binary Tree Paths

Find all root-to-leaf paths in a binary tree

Convert Sorted Array to Binary Search Tree

Convert a sorted array to a binary search tree

Maximum Difference Between Node and Ancestor

Find the maximum difference between a node and its ancestor in a binary tree

Path Sum III

Count downward paths that sum to target using prefix sums and DFS

Binary Tree Inorder Traversal

Traverse tree inorder using DFS and stack

Minimum Distance Between BST Nodes

Find the minimum distance between any two nodes in a BST

Validate Binary Search Tree

Check if a binary tree satisfies BST properties using recursive DFS

Kth Smallest Element in a BST

Find the kth smallest element in a BST using iterative inorder traversal

Binary Tree Postorder Traversal

Traverse tree postorder using DFS and stack

Invert Binary Tree

Invert a binary tree using DFS and stack

Diameter of Binary Tree

Find the diameter of a binary tree using recursion

Lowest Common Ancestor of a Binary Tree

Find the lowest common ancestor of two nodes in a binary tree using recursion

Find Duplicate Subtrees

Find duplicate subtrees in a binary tree using serialization

Flatten Binary Tree to Linked List

Flatten tree to right-skewed linked list in-place using Morris Traversal

Distribute Coins in Binary Tree

Distribute coins to each node in a binary tree so that every node has exactly one coin

House Robber III

Find maximum amount of money the thief can rob from a binary tree

Binary Tree Maximum Path Sum

Find maximum path sum in tree where path can start and end at any node

Binary Tree Cameras

Find minimum number of cameras to cover all nodes in a binary tree

BST

Trim Binary Search Tree

Trim BST to range [low, high] using recursive pruning and restructuring

Tries

Search Suggestions System

Generate product suggestions for each prefix using binary search

Word Search II

Find all words from dictionary in board using Trie and DFS backtracking

Heap

Sort Characters By Frequency

Sort characters by frequency using min-heap

Furthest Building You Can Reach

Find furthest building reachable with bricks and ladders using min-heap

Top K Frequent Elements

Find top k frequent elements using min-heap

Find Median from Data Stream

Find median from data stream using two heaps

IPO

Maximize capital by selecting k most profitable projects using max-heap

K Closest Points to Origin

Find k closest points to origin using max-heap to track distances

Find K Pairs with Smallest Sums

Find k pairs with smallest sums using min-heap

Merge k Sorted Lists

Merge k sorted lists using min-heap

Intervals

Merge Intervals

Merge all overlapping intervals on a timeline

Insert Interval

Insert a new interval into a list of intervals

Minimum Number of Arrows to Burst Balloons

Find minimum arrows needed to burst all balloons using greedy algorithm

Non-overlapping Intervals

Find maximum number of non-overlapping intervals using greedy algorithm

Kth Smallest Element in Sorted Matrix

Find kth smallest element using binary search on value range

Maximum Number of Events That Can Be Attended

Attend the maximum number of events using a greedy min-heap approach

Greedy

Jump Game II

Find minimum jumps to reach the end using greedy BFS approach

Gas Station

Find starting gas station to complete circular route using greedy algorithm

Graph

Depth First Search

Traverse a graph using Depth First Search

Number of Islands

Count separate islands in a 2D grid using BFS flood-fill

Time Needed to Inform All Employees

Find the time needed to inform all employees using DFS with memoization

Employee Importance

Find the importance of an employee using DFS with memoization

Clone Graph

Clone a graph using DFS

Is Graph Bipartite?

Check if a graph is bipartite using DFS with coloring

All Nodes Distance K in Binary Tree

Find all nodes exactly K edges away from target using BFS with parent links

Rotting Oranges

Find minimum time for all oranges to rot using multi-source BFS

Word Ladder

Find shortest word transformation sequence using BFS

Course Schedule II

Find valid course order using DFS topological sort on prerequisite graph

Find Eventual Safe States

Find eventual safe states in a graph using DFS

Minimum Height Trees

Find minimum height trees in a graph using BFS

Number of Provinces

Count connected components in adjacency matrix using DFS

Redundant Connection

Find redundant connection in a graph using Union-Find

Minimize Malware Spread

Find redundant connection in a graph using Union-Find

Min Cost to Connect All Points

Find minimum cost to connect all points using Kruskal's algorithm

Dynamic Programming

Longest Increasing Subsequence

Find the length of the longest increasing subsequence

Minimum Path Sum

Find the minimum path sum from top-left to bottom-right in a grid

Russian Doll Envelopes

Find max envelopes that can be Russian dolled using Sort + LIS

Climbing Stairs

Find the number of ways to climb to the top of the stairs

Min Cost Climbing Stairs

Find the minimum cost to climb to the top of the stairs

House Robber

Find maximum money to rob from houses using dynamic programming

House Robber II

Find maximum money to rob from houses in a circle using dynamic programming

Unique Paths II

Find number of unique paths to reach the bottom-right corner of a grid with obstacles using dynamic programming

Count Square Submatrices with All Ones

Find number of square submatrices with all ones using dynamic programming

Maximum Number of Points with Cost

Find maximum number of points with cost using dynamic programming

Burst Balloons

Find maximum number of points with cost using dynamic programming

Maximum Profit in Job Scheduling

Find maximum profit in job scheduling using dynamic programming

Longest Common Subsequence

Find length of longest subsequence common to both strings using dynamic programming

Edit Distance

Find minimum number of operations to convert one string to another using dynamic programming

Longest Palindromic Subsequence

Find length of longest palindromic subsequence using dynamic programming

Decode Ways

Find number of ways to decode a string using dynamic programming

Wildcard Matching

Check if one string matches the pattern using dynamic programming

Distinct Subsequences

Count number of ways to get t from s using dynamic programming

Coin Change

Find minimum number of coins to make amount using dynamic programming

Coin Change II

Count number of ways to make amount using coins with dynamic programming

Perfect Squares

Find minimum number of perfect squares that sum to n using dynamic programming

Partition Equal Subset Sum

Check if the array can be partitioned into two subsets with equal sum using dynamic programming

Target Sum

Find number of ways to target sum using dynamic programming

Last Stone Weight II

Find the minimum weight of the last stone using dynamic programming