Difficulty × Topics Matrix¶

2026-01-102026-01-10

Topics organized by difficulty level. Start with Easy, progress to Hard.

🟢 Easy (146 problems)¶

Array (25)¶

-LeetCode 1 - Two Sum · Solution -LeetCode 26 - Remove Duplicates from Sorted Array · Solution -LeetCode 27 - Remove Element · Solution -LeetCode 35 - Search Insert Position · Solution -LeetCode 66 - Plus One · Solution -LeetCode 88 - Merge Sorted Array · Solution -LeetCode 121 - Best Time to Buy and Sell Stock · Solution -LeetCode 136 - Single Number · Solution -LeetCode 217 - Contains Duplicate · Solution -LeetCode 252 - Meeting Rooms · Solution -LeetCode 268 - Missing Number · Solution -LeetCode 283 - Move Zeroes · Solution -LeetCode 303 - Range Sum Query - Immutable · Solution -LeetCode 455 - Assign Cookies · Solution -LeetCode 496 - Next Greater Element I · Solution -LeetCode 605 - Can Place Flowers · Solution -LeetCode 704 - Binary Search · Solution -LeetCode 746 - Min Cost Climbing Stairs · Solution -LeetCode 905 - Sort Array By Parity · Solution -LeetCode 914 - X of a Kind in a Deck of Cards · Solution -LeetCode 922 - Sort Array By Parity II · Solution -LeetCode 977 - Squares of a Sorted Array · Solution -LeetCode 1046 - Last Stone Weight · Solution -LeetCode 1909 - Remove One Element to Make the Array Strictly Increasing · Solution -LeetCode 1979 - Find Greatest Common Divisor of Array · Solution

Two Pointers (13)¶

-LeetCode 26 - Remove Duplicates from Sorted Array · Solution -LeetCode 27 - Remove Element · Solution -LeetCode 88 - Merge Sorted Array · Solution -LeetCode 125 - Valid Palindrome · Solution -LeetCode 141 - Linked List Cycle · Solution -LeetCode 202 - Happy Number · Solution -LeetCode 283 - Move Zeroes · Solution -LeetCode 455 - Assign Cookies · Solution -LeetCode 680 - Valid Palindrome II · Solution -LeetCode 876 - Middle of the Linked List · Solution -LeetCode 905 - Sort Array By Parity · Solution -LeetCode 922 - Sort Array By Parity II · Solution -LeetCode 977 - Squares of a Sorted Array · Solution

Math (8)¶

-LeetCode 66 - Plus One · Solution -LeetCode 70 - Climbing Stairs · Solution -LeetCode 168 - Excel Sheet Column Title · Solution -LeetCode 202 - Happy Number · Solution -LeetCode 268 - Missing Number · Solution -LeetCode 914 - X of a Kind in a Deck of Cards · Solution -LeetCode 1979 - Find Greatest Common Divisor of Array · Solution -LeetCode 2591 - Distribute Money to Maximum Children · Solution

Depth First Search (8)¶

-LeetCode 94 - Binary Tree Inorder Traversal · Solution -LeetCode 100 - Same Tree · Solution -LeetCode 104 - Maximum Depth of Binary Tree · Solution -LeetCode 110 - Balanced Binary Tree · Solution -LeetCode 226 - Invert Binary Tree · Solution -LeetCode 543 - Diameter of Binary Tree · Solution -LeetCode 572 - Subtree of Another Tree · Solution -LeetCode 1971 - Find if Path Exists in Graph · Solution

Hash Table (8)¶

-LeetCode 1 - Two Sum · Solution -LeetCode 141 - Linked List Cycle · Solution -LeetCode 202 - Happy Number · Solution -LeetCode 217 - Contains Duplicate · Solution -LeetCode 242 - Valid Anagram · Solution -LeetCode 268 - Missing Number · Solution -LeetCode 496 - Next Greater Element I · Solution -LeetCode 2423 - Remove Letter To Equalize Frequency · Solution

Sorting (8)¶

-LeetCode 88 - Merge Sorted Array · Solution -LeetCode 217 - Contains Duplicate · Solution -LeetCode 242 - Valid Anagram · Solution -LeetCode 252 - Meeting Rooms · Solution -LeetCode 268 - Missing Number · Solution -LeetCode 455 - Assign Cookies · Solution -LeetCode 905 - Sort Array By Parity · Solution -LeetCode 977 - Squares of a Sorted Array · Solution

Tree (8)¶

-LeetCode 94 - Binary Tree Inorder Traversal · Solution -LeetCode 100 - Same Tree · Solution -LeetCode 104 - Maximum Depth of Binary Tree · Solution -LeetCode 110 - Balanced Binary Tree · Solution -LeetCode 226 - Invert Binary Tree · Solution -LeetCode 543 - Diameter of Binary Tree · Solution -LeetCode 572 - Subtree of Another Tree · Solution -LeetCode 703 - Kth Largest Element in a Stream · Solution

Binary Tree (8)¶

-LeetCode 94 - Binary Tree Inorder Traversal · Solution -LeetCode 100 - Same Tree · Solution -LeetCode 104 - Maximum Depth of Binary Tree · Solution -LeetCode 110 - Balanced Binary Tree · Solution -LeetCode 226 - Invert Binary Tree · Solution -LeetCode 543 - Diameter of Binary Tree · Solution -LeetCode 572 - Subtree of Another Tree · Solution -LeetCode 703 - Kth Largest Element in a Stream · Solution

String (6)¶

-LeetCode 20 - Valid Parentheses · Solution -LeetCode 125 - Valid Palindrome · Solution -LeetCode 168 - Excel Sheet Column Title · Solution -LeetCode 242 - Valid Anagram · Solution -LeetCode 680 - Valid Palindrome II · Solution -LeetCode 2423 - Remove Letter To Equalize Frequency · Solution

Bit Manipulation (5)¶

-LeetCode 136 - Single Number · Solution -LeetCode 190 - Reverse Bits · Solution -LeetCode 191 - Number of 1 Bits · Solution -LeetCode 268 - Missing Number · Solution -LeetCode 338 - Counting Bits · Solution

Greedy (4)¶

-LeetCode 455 - Assign Cookies · Solution -LeetCode 605 - Can Place Flowers · Solution -LeetCode 680 - Valid Palindrome II · Solution -LeetCode 2591 - Distribute Money to Maximum Children · Solution

Breadth First Search (4)¶

-LeetCode 100 - Same Tree · Solution -LeetCode 104 - Maximum Depth of Binary Tree · Solution -LeetCode 226 - Invert Binary Tree · Solution -LeetCode 1971 - Find if Path Exists in Graph · Solution

Linked List (4)¶

-LeetCode 21 - Merge Two Sorted Lists · Solution -LeetCode 141 - Linked List Cycle · Solution -LeetCode 206 - Reverse Linked List · Solution -LeetCode 876 - Middle of the Linked List · Solution

Dynamic Programming (4)¶

-LeetCode 70 - Climbing Stairs · Solution -LeetCode 121 - Best Time to Buy and Sell Stock · Solution -LeetCode 338 - Counting Bits · Solution -LeetCode 746 - Min Cost Climbing Stairs · Solution

Binary Search (3)¶

-LeetCode 35 - Search Insert Position · Solution -LeetCode 268 - Missing Number · Solution -LeetCode 704 - Binary Search · Solution

Stack (3)¶

-LeetCode 20 - Valid Parentheses · Solution -LeetCode 94 - Binary Tree Inorder Traversal · Solution -LeetCode 496 - Next Greater Element I · Solution

String (2)¶

-LeetCode 459 - Repeated Substring Pattern -LeetCode 28 - Find the Index of the First Occurrence in a String

String Matching (2)¶

-LeetCode 459 - Repeated Substring Pattern -LeetCode 28 - Find the Index of the First Occurrence in a String

Recursion (2)¶

-LeetCode 21 - Merge Two Sorted Lists · Solution -LeetCode 206 - Reverse Linked List · Solution

Counting (2)¶

-LeetCode 914 - X of a Kind in a Deck of Cards · Solution -LeetCode 2423 - Remove Letter To Equalize Frequency · Solution

Design (2)¶

-LeetCode 303 - Range Sum Query - Immutable · Solution -LeetCode 703 - Kth Largest Element in a Stream · Solution

Heap (2)¶

-LeetCode 703 - Kth Largest Element in a Stream · Solution -LeetCode 1046 - Last Stone Weight · Solution

Divide And Conquer (2)¶

-LeetCode 190 - Reverse Bits · Solution -LeetCode 191 - Number of 1 Bits · Solution

Union Find (1)¶

-LeetCode 1971 - Find if Path Exists in Graph · Solution

Graph (1)¶

-LeetCode 1971 - Find if Path Exists in Graph · Solution

Hash-Table (1)¶

-LeetCode 914 - X of a Kind in a Deck of Cards · Solution

Number-Theory (1)¶

-LeetCode 914 - X of a Kind in a Deck of Cards · Solution

Binary Search Tree (1)¶

-LeetCode 703 - Kth Largest Element in a Stream · Solution

Data Stream (1)¶

-LeetCode 703 - Kth Largest Element in a Stream · Solution

Prefix Sum (1)¶

-LeetCode 303 - Range Sum Query - Immutable · Solution

String Matching (1)¶

-LeetCode 572 - Subtree of Another Tree · Solution

Hash Function (1)¶

-LeetCode 572 - Subtree of Another Tree · Solution

Number Theory (1)¶

-LeetCode 1979 - Find Greatest Common Divisor of Array · Solution

Memoization (1)¶

-LeetCode 70 - Climbing Stairs · Solution

Monotonic Stack (1)¶

-LeetCode 496 - Next Greater Element I · Solution

Two Pointers (1)¶

-LeetCode 28 - Find the Index of the First Occurrence in a String

🟡 Medium (582 problems)¶

Array (103)¶

-LeetCode 11 - Container With Most Water · Solution -LeetCode 15 - 3Sum · Solution -LeetCode 16 - 3Sum Closest · Solution -LeetCode 31 - Next Permutation · Solution -LeetCode 33 - Search in Rotated Sorted Array · Solution -LeetCode 34 - Find First and Last Position of Element in Sorted Array · Solution -LeetCode 36 - Valid Sudoku · Solution -LeetCode 39 - Combination Sum · Solution -LeetCode 40 - Combination Sum II · Solution -LeetCode 45 - Jump Game II · Solution -LeetCode 46 - Permutations · Solution -LeetCode 47 - Permutations II · Solution -LeetCode 48 - Rotate Image · Solution -LeetCode 49 - Group Anagrams · Solution -LeetCode 53 - Maximum Subarray · Solution -LeetCode 54 - Spiral Matrix · Solution -LeetCode 55 - Jump Game · Solution -LeetCode 56 - Merge Intervals · Solution -LeetCode 57 - Insert Interval · Solution -LeetCode 73 - Set Matrix Zeroes · Solution -LeetCode 74 - Search a 2D Matrix · Solution -LeetCode 75 - Sort Colors · Solution -LeetCode 78 - Subsets · Solution -LeetCode 79 - Word Search · Solution -LeetCode 80 - Remove Duplicates from Sorted Array II · Solution -LeetCode 81 - Search in Rotated Sorted Array II · Solution -LeetCode 90 - Subsets II · Solution -LeetCode 105 - Construct Binary Tree from Preorder and Inorder Traversal · Solution -LeetCode 128 - Longest Consecutive Sequence · Solution -LeetCode 130 - Surrounded Regions · Solution -LeetCode 134 - Gas Station · Solution -LeetCode 139 - Word Break · Solution -LeetCode 150 - Evaluate Reverse Polish Notation · Solution -LeetCode 152 - Maximum Product Subarray · Solution -LeetCode 153 - Find Minimum in Rotated Sorted Array · Solution -LeetCode 162 - Find Peak Element · Solution -LeetCode 198 - House Robber · Solution -LeetCode 200 - Number of Islands · Solution -LeetCode 204 - Count Primes · Solution -LeetCode 209 - Minimum Size Subarray Sum · Solution -LeetCode 213 - House Robber II · Solution -LeetCode 215 - Kth Largest Element in an Array · Solution -LeetCode 216 - Combination Sum III · Solution -LeetCode 238 - Product of Array Except Self · Solution -LeetCode 253 - Meeting Rooms II · Solution -LeetCode 286 - Walls and Gates · Solution -LeetCode 300 - Longest Increasing Subsequence · Solution -LeetCode 304 - Range Sum Query 2D - Immutable · Solution -LeetCode 307 - Range Sum Query - Mutable · Solution -LeetCode 309 - Best Time to Buy and Sell Stock with Cooldown · Solution -LeetCode 322 - Coin Change · Solution -LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 416 - Partition Equal Subset Sum · Solution -LeetCode 417 - Pacific Atlantic Water Flow · Solution -LeetCode 435 - Non-overlapping Intervals · Solution -LeetCode 452 - Minimum Number of Arrows to Burst Balloons · Solution -LeetCode 494 - Target Sum · Solution -LeetCode 503 - Next Greater Element II · Solution -LeetCode 518 - Coin Change II · Solution -LeetCode 523 - Continuous Subarray Sum · Solution -LeetCode 525 - Contiguous Array · Solution -LeetCode 542 - 01 Matrix · Solution -LeetCode 560 - Subarray Sum Equals K · Solution -LeetCode 621 - Task Scheduler · Solution -LeetCode 648 - Replace Words · Solution -LeetCode 665 - Non-decreasing Array · Solution -LeetCode 695 - Max Area of Island · Solution -LeetCode 721 - Accounts Merge · Solution -LeetCode 739 - Daily Temperatures · Solution -LeetCode 846 - Hand of Straights · Solution -LeetCode 853 - Car Fleet · Solution -LeetCode 875 - Koko Eating Bananas · Solution -LeetCode 907 - Sum of Subarray Minimums · Solution -LeetCode 973 - K Closest Points to Origin · Solution -LeetCode 986 - Interval List Intersections · Solution -LeetCode 990 - Satisfiability of Equality Equations · Solution -LeetCode 994 - Rotting Oranges · Solution -LeetCode 1011 - Capacity To Ship Packages Within D Days · Solution -LeetCode 1029 - Two City Scheduling · Solution -LeetCode 1094 - Car Pooling · Solution -LeetCode 1109 - Corporate Flight Bookings · Solution -LeetCode 1191 - K-Concatenation Maximum Sum · Solution -LeetCode 1268 - Search Suggestions System · Solution -LeetCode 1438 - Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit · Solution -LeetCode 1584 - Min Cost to Connect All Points · Solution -LeetCode 1631 - Path With Minimum Effort · Solution -LeetCode 1648 - Sell Diminishing-Valued Colored Balls · Solution -LeetCode 1899 - Merge Triplets to Form Target Triplet · Solution -LeetCode 2013 - Detect Squares · Solution -LeetCode 2029 - Stone Game IX · Solution -LeetCode 2104 - Sum of Subarray Ranges · Solution -LeetCode 2195 - Append K Integers With Minimal Sum · Solution -LeetCode 2202 - Maximize the Topmost Element After K Moves · Solution -LeetCode 2280 - Minimum Lines to Represent a Line Chart · Solution -LeetCode 2289 - Steps to Make Array Non-decreasing · Solution -LeetCode 2332 - The Latest Time to Catch a Bus · Solution -LeetCode 2333 - Minimum Sum of Squared Difference · Solution -LeetCode 2556 - Disconnect Path in a Binary Matrix by at Most One Flip · Solution -LeetCode 2572 - Count the Number of Square-Free Subsets · Solution -LeetCode 2708 - Maximum Strength of a Group · Solution -LeetCode 2731 - Movement of Robots · Solution -LeetCode 2741 - Special Permutations · Solution -LeetCode 2746 - Decremental String Concatenation · Solution

String (33)¶

-LeetCode 3 - Longest Substring Without Repeating Characters · Solution -LeetCode 5 - Longest Palindromic Substring · Solution -LeetCode 8 - String to Integer (atoi) · Solution(atoi) -LeetCode 17 - Letter Combinations of a Phone Number · Solution -LeetCode 22 - Generate Parentheses · Solution -LeetCode 43 - Multiply Strings · Solution -LeetCode 49 - Group Anagrams · Solution -LeetCode 91 - Decode Ways · Solution -LeetCode 93 - Restore IP Addresses · Solution -LeetCode 97 - Interleaving String · Solution -LeetCode 131 - Palindrome Partitioning · Solution -LeetCode 139 - Word Break · Solution -LeetCode 208 - Implement Trie (Prefix Tree) · Solution(Prefix Tree) -LeetCode 211 - Design Add and Search Words Data Structure · Solution -LeetCode 271 - Encode and Decode Strings · Solution -LeetCode 316 - Remove Duplicate Letters · Solution -LeetCode 340 - Longest Substring with At Most K Distinct Characters · Solution -LeetCode 402 - Remove K Digits · Solution -LeetCode 424 - Longest Repeating Character Replacement · Solution -LeetCode 438 - Find All Anagrams in a String · Solution -LeetCode 468 - Validate IP Address · Solution -LeetCode 567 - Permutation in String · Solution -LeetCode 647 - Palindromic Substrings · Solution -LeetCode 648 - Replace Words · Solution -LeetCode 678 - Valid Parenthesis String · Solution -LeetCode 721 - Accounts Merge · Solution -LeetCode 763 - Partition Labels · Solution -LeetCode 981 - Time Based Key-Value Store · Solution -LeetCode 990 - Satisfiability of Equality Equations · Solution -LeetCode 1268 - Search Suggestions System · Solution -LeetCode 1871 - Jump Game VII · Solution -LeetCode 2531 - Make Number of Distinct Characters Equal · Solution -LeetCode 2746 - Decremental String Concatenation · Solution

Dynamic Programming (32)¶

-LeetCode 5 - Longest Palindromic Substring · Solution -LeetCode 22 - Generate Parentheses · Solution -LeetCode 45 - Jump Game II · Solution -LeetCode 53 - Maximum Subarray · Solution -LeetCode 55 - Jump Game · Solution -LeetCode 62 - Unique Paths · Solution -LeetCode 91 - Decode Ways · Solution -LeetCode 97 - Interleaving String · Solution -LeetCode 131 - Palindrome Partitioning · Solution -LeetCode 139 - Word Break · Solution -LeetCode 152 - Maximum Product Subarray · Solution -LeetCode 198 - House Robber · Solution -LeetCode 213 - House Robber II · Solution -LeetCode 300 - Longest Increasing Subsequence · Solution -LeetCode 309 - Best Time to Buy and Sell Stock with Cooldown · Solution -LeetCode 322 - Coin Change · Solution -LeetCode 337 - House Robber III · Solution -LeetCode 416 - Partition Equal Subset Sum · Solution -LeetCode 435 - Non-overlapping Intervals · Solution -LeetCode 494 - Target Sum · Solution -LeetCode 518 - Coin Change II · Solution -LeetCode 542 - 01 Matrix · Solution -LeetCode 647 - Palindromic Substrings · Solution -LeetCode 678 - Valid Parenthesis String · Solution -LeetCode 787 - Cheapest Flights Within K Stops · Solution -LeetCode 907 - Sum of Subarray Minimums · Solution -LeetCode 1191 - K-Concatenation Maximum Sum · Solution -LeetCode 1871 - Jump Game VII · Solution -LeetCode 2310 - Sum of Numbers With Units Digit K · Solution -LeetCode 2556 - Disconnect Path in a Binary Matrix by at Most One Flip · Solution -LeetCode 2572 - Count the Number of Square-Free Subsets · Solution -LeetCode 2746 - Decremental String Concatenation · Solution

Hash Table (29)¶

-LeetCode 3 - Longest Substring Without Repeating Characters · Solution -LeetCode 17 - Letter Combinations of a Phone Number · Solution -LeetCode 36 - Valid Sudoku · Solution -LeetCode 49 - Group Anagrams · Solution -LeetCode 73 - Set Matrix Zeroes · Solution -LeetCode 105 - Construct Binary Tree from Preorder and Inorder Traversal · Solution -LeetCode 128 - Longest Consecutive Sequence · Solution -LeetCode 133 - Clone Graph · Solution -LeetCode 138 - Copy List with Random Pointer · Solution -LeetCode 139 - Word Break · Solution -LeetCode 142 - Linked List Cycle II · Solution -LeetCode 146 - LRU Cache · Solution -LeetCode 208 - Implement Trie (Prefix Tree) · Solution(Prefix Tree) -LeetCode 340 - Longest Substring with At Most K Distinct Characters · Solution -LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 355 - Design Twitter · Solution -LeetCode 424 - Longest Repeating Character Replacement · Solution -LeetCode 438 - Find All Anagrams in a String · Solution -LeetCode 523 - Continuous Subarray Sum · Solution -LeetCode 525 - Contiguous Array · Solution -LeetCode 560 - Subarray Sum Equals K · Solution -LeetCode 567 - Permutation in String · Solution -LeetCode 621 - Task Scheduler · Solution -LeetCode 648 - Replace Words · Solution -LeetCode 763 - Partition Labels · Solution -LeetCode 846 - Hand of Straights · Solution -LeetCode 981 - Time Based Key-Value Store · Solution -LeetCode 2013 - Detect Squares · Solution -LeetCode 2531 - Make Number of Distinct Characters Equal · Solution

Sorting (25)¶

-LeetCode 15 - 3Sum · Solution -LeetCode 16 - 3Sum Closest · Solution -LeetCode 49 - Group Anagrams · Solution -LeetCode 56 - Merge Intervals · Solution -LeetCode 75 - Sort Colors · Solution -LeetCode 215 - Kth Largest Element in an Array · Solution -LeetCode 253 - Meeting Rooms II · Solution -LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 435 - Non-overlapping Intervals · Solution -LeetCode 452 - Minimum Number of Arrows to Burst Balloons · Solution -LeetCode 621 - Task Scheduler · Solution -LeetCode 721 - Accounts Merge · Solution -LeetCode 846 - Hand of Straights · Solution -LeetCode 853 - Car Fleet · Solution -LeetCode 973 - K Closest Points to Origin · Solution -LeetCode 1029 - Two City Scheduling · Solution -LeetCode 1094 - Car Pooling · Solution -LeetCode 1268 - Search Suggestions System · Solution -LeetCode 1648 - Sell Diminishing-Valued Colored Balls · Solution -LeetCode 2195 - Append K Integers With Minimal Sum · Solution -LeetCode 2280 - Minimum Lines to Represent a Line Chart · Solution -LeetCode 2332 - The Latest Time to Catch a Bus · Solution -LeetCode 2333 - Minimum Sum of Squared Difference · Solution -LeetCode 2708 - Maximum Strength of a Group · Solution -LeetCode 2731 - Movement of Robots · Solution

Depth First Search (22)¶

-LeetCode 130 - Surrounded Regions · Solution -LeetCode 133 - Clone Graph · Solution -LeetCode 199 - Binary Tree Right Side View · Solution -LeetCode 200 - Number of Islands · Solution -LeetCode 207 - Course Schedule · Solution -LeetCode 210 - Course Schedule II · Solution -LeetCode 211 - Design Add and Search Words Data Structure · Solution -LeetCode 230 - Kth Smallest Element in a BST · Solution -LeetCode 235 - Lowest Common Ancestor of a Binary Search Tree · Solution -LeetCode 337 - House Robber III · Solution -LeetCode 417 - Pacific Atlantic Water Flow · Solution -LeetCode 547 - Number of Provinces · Solution -LeetCode 684 - Redundant Connection · Solution -LeetCode 695 - Max Area of Island · Solution -LeetCode 721 - Accounts Merge · Solution -LeetCode 743 - Network Delay Time · Solution -LeetCode 785 - Is Graph Bipartite? · Solution -LeetCode 787 - Cheapest Flights Within K Stops · Solution -LeetCode 802 - Find Eventual Safe States · Solution -LeetCode 841 - Keys and Rooms · Solution -LeetCode 1319 - Number of Operations to Make Network Connected · Solution -LeetCode 1631 - Path With Minimum Effort · Solution

Math (22)¶

-LeetCode 2 - Add Two Numbers · Solution -LeetCode 7 - Reverse Integer · Solution -LeetCode 29 - Divide Two Integers · Solution -LeetCode 43 - Multiply Strings · Solution -LeetCode 48 - Rotate Image · Solution -LeetCode 50 - Pow(x, n) · Solution(x, n) -LeetCode 62 - Unique Paths · Solution -LeetCode 150 - Evaluate Reverse Polish Notation · Solution -LeetCode 204 - Count Primes · Solution -LeetCode 371 - Sum of Two Integers · Solution -LeetCode 523 - Continuous Subarray Sum · Solution -LeetCode 866 - Prime Palindrome · Solution -LeetCode 973 - K Closest Points to Origin · Solution -LeetCode 1648 - Sell Diminishing-Valued Colored Balls · Solution -LeetCode 2029 - Stone Game IX · Solution -LeetCode 2069 - Walking Robot Simulation II · Solution -LeetCode 2195 - Append K Integers With Minimal Sum · Solution -LeetCode 2280 - Minimum Lines to Represent a Line Chart · Solution -LeetCode 2310 - Sum of Numbers With Units Digit K · Solution -LeetCode 2333 - Minimum Sum of Squared Difference · Solution -LeetCode 2550 - Count Collisions of Monkeys on a Polygon · Solution -LeetCode 2572 - Count the Number of Square-Free Subsets · Solution

Greedy (21)¶

-LeetCode 11 - Container With Most Water · Solution -LeetCode 45 - Jump Game II · Solution -LeetCode 55 - Jump Game · Solution -LeetCode 134 - Gas Station · Solution -LeetCode 253 - Meeting Rooms II · Solution -LeetCode 316 - Remove Duplicate Letters · Solution -LeetCode 402 - Remove K Digits · Solution -LeetCode 435 - Non-overlapping Intervals · Solution -LeetCode 452 - Minimum Number of Arrows to Burst Balloons · Solution -LeetCode 621 - Task Scheduler · Solution -LeetCode 665 - Non-decreasing Array · Solution -LeetCode 678 - Valid Parenthesis String · Solution -LeetCode 763 - Partition Labels · Solution -LeetCode 846 - Hand of Straights · Solution -LeetCode 1029 - Two City Scheduling · Solution -LeetCode 1648 - Sell Diminishing-Valued Colored Balls · Solution -LeetCode 1899 - Merge Triplets to Form Target Triplet · Solution -LeetCode 2195 - Append K Integers With Minimal Sum · Solution -LeetCode 2202 - Maximize the Topmost Element After K Moves · Solution -LeetCode 2310 - Sum of Numbers With Units Digit K · Solution -LeetCode 2708 - Maximum Strength of a Group · Solution

Breadth First Search (21)¶

-LeetCode 102 - Binary Tree Level Order Traversal · Solution -LeetCode 130 - Surrounded Regions · Solution -LeetCode 133 - Clone Graph · Solution -LeetCode 199 - Binary Tree Right Side View · Solution -LeetCode 200 - Number of Islands · Solution -LeetCode 207 - Course Schedule · Solution -LeetCode 210 - Course Schedule II · Solution -LeetCode 286 - Walls and Gates · Solution -LeetCode 417 - Pacific Atlantic Water Flow · Solution -LeetCode 542 - 01 Matrix · Solution -LeetCode 547 - Number of Provinces · Solution -LeetCode 684 - Redundant Connection · Solution -LeetCode 695 - Max Area of Island · Solution -LeetCode 743 - Network Delay Time · Solution -LeetCode 785 - Is Graph Bipartite? · Solution -LeetCode 787 - Cheapest Flights Within K Stops · Solution -LeetCode 802 - Find Eventual Safe States · Solution -LeetCode 841 - Keys and Rooms · Solution -LeetCode 994 - Rotting Oranges · Solution -LeetCode 1319 - Number of Operations to Make Network Connected · Solution -LeetCode 1631 - Path With Minimum Effort · Solution

Matrix (16)¶

-LeetCode 36 - Valid Sudoku · Solution -LeetCode 48 - Rotate Image · Solution -LeetCode 54 - Spiral Matrix · Solution -LeetCode 73 - Set Matrix Zeroes · Solution -LeetCode 74 - Search a 2D Matrix · Solution -LeetCode 79 - Word Search · Solution -LeetCode 130 - Surrounded Regions · Solution -LeetCode 200 - Number of Islands · Solution -LeetCode 286 - Walls and Gates · Solution -LeetCode 304 - Range Sum Query 2D - Immutable · Solution -LeetCode 417 - Pacific Atlantic Water Flow · Solution -LeetCode 542 - 01 Matrix · Solution -LeetCode 695 - Max Area of Island · Solution -LeetCode 994 - Rotting Oranges · Solution -LeetCode 1631 - Path With Minimum Effort · Solution -LeetCode 2556 - Disconnect Path in a Binary Matrix by at Most One Flip · Solution

Graph (15)¶

-LeetCode 133 - Clone Graph · Solution -LeetCode 207 - Course Schedule · Solution -LeetCode 210 - Course Schedule II · Solution -LeetCode 261 - Graph Valid Tree · Solution -LeetCode 547 - Number of Provinces · Solution -LeetCode 684 - Redundant Connection · Solution -LeetCode 743 - Network Delay Time · Solution -LeetCode 785 - Is Graph Bipartite? · Solution -LeetCode 787 - Cheapest Flights Within K Stops · Solution -LeetCode 802 - Find Eventual Safe States · Solution -LeetCode 841 - Keys and Rooms · Solution -LeetCode 990 - Satisfiability of Equality Equations · Solution -LeetCode 1319 - Number of Operations to Make Network Connected · Solution -LeetCode 1584 - Min Cost to Connect All Points · Solution -LeetCode 1631 - Path With Minimum Effort · Solution

Backtracking (14)¶

-LeetCode 17 - Letter Combinations of a Phone Number · Solution -LeetCode 22 - Generate Parentheses · Solution -LeetCode 39 - Combination Sum · Solution -LeetCode 40 - Combination Sum II · Solution -LeetCode 46 - Permutations · Solution -LeetCode 47 - Permutations II · Solution -LeetCode 77 - Combinations · Solution -LeetCode 78 - Subsets · Solution -LeetCode 79 - Word Search · Solution -LeetCode 90 - Subsets II · Solution -LeetCode 93 - Restore IP Addresses · Solution -LeetCode 131 - Palindrome Partitioning · Solution -LeetCode 216 - Combination Sum III · Solution -LeetCode 494 - Target Sum · Solution

Binary Search (14)¶

-LeetCode 33 - Search in Rotated Sorted Array · Solution -LeetCode 34 - Find First and Last Position of Element in Sorted Array · Solution -LeetCode 74 - Search a 2D Matrix · Solution -LeetCode 81 - Search in Rotated Sorted Array II · Solution -LeetCode 153 - Find Minimum in Rotated Sorted Array · Solution -LeetCode 162 - Find Peak Element · Solution -LeetCode 209 - Minimum Size Subarray Sum · Solution -LeetCode 300 - Longest Increasing Subsequence · Solution -LeetCode 875 - Koko Eating Bananas · Solution -LeetCode 981 - Time Based Key-Value Store · Solution -LeetCode 1011 - Capacity To Ship Packages Within D Days · Solution -LeetCode 1268 - Search Suggestions System · Solution -LeetCode 1631 - Path With Minimum Effort · Solution -LeetCode 2333 - Minimum Sum of Squared Difference · Solution

Two Pointers (14)¶

-LeetCode 11 - Container With Most Water · Solution -LeetCode 15 - 3Sum · Solution -LeetCode 16 - 3Sum Closest · Solution -LeetCode 19 - Remove Nth Node From End of List · Solution -LeetCode 31 - Next Permutation · Solution -LeetCode 75 - Sort Colors · Solution -LeetCode 80 - Remove Duplicates from Sorted Array II · Solution -LeetCode 142 - Linked List Cycle II · Solution -LeetCode 143 - Reorder List · Solution -LeetCode 253 - Meeting Rooms II · Solution -LeetCode 567 - Permutation in String · Solution -LeetCode 647 - Palindromic Substrings · Solution -LeetCode 763 - Partition Labels · Solution -LeetCode 986 - Interval List Intersections · Solution

Stack (13)¶

-LeetCode 143 - Reorder List · Solution -LeetCode 150 - Evaluate Reverse Polish Notation · Solution -LeetCode 155 - Min Stack · Solution -LeetCode 316 - Remove Duplicate Letters · Solution -LeetCode 402 - Remove K Digits · Solution -LeetCode 503 - Next Greater Element II · Solution -LeetCode 678 - Valid Parenthesis String · Solution -LeetCode 739 - Daily Temperatures · Solution -LeetCode 853 - Car Fleet · Solution -LeetCode 901 - Online Stock Span · Solution -LeetCode 907 - Sum of Subarray Minimums · Solution -LeetCode 2104 - Sum of Subarray Ranges · Solution -LeetCode 2289 - Steps to Make Array Non-decreasing · Solution

Union Find (13)¶

-LeetCode 128 - Longest Consecutive Sequence · Solution -LeetCode 130 - Surrounded Regions · Solution -LeetCode 200 - Number of Islands · Solution -LeetCode 261 - Graph Valid Tree · Solution -LeetCode 547 - Number of Provinces · Solution -LeetCode 684 - Redundant Connection · Solution -LeetCode 695 - Max Area of Island · Solution -LeetCode 721 - Accounts Merge · Solution -LeetCode 785 - Is Graph Bipartite? · Solution -LeetCode 990 - Satisfiability of Equality Equations · Solution -LeetCode 1319 - Number of Operations to Make Network Connected · Solution -LeetCode 1584 - Min Cost to Connect All Points · Solution -LeetCode 1631 - Path With Minimum Effort · Solution

Design (13)¶

-LeetCode 146 - LRU Cache · Solution -LeetCode 155 - Min Stack · Solution -LeetCode 208 - Implement Trie (Prefix Tree) · Solution(Prefix Tree) -LeetCode 211 - Design Add and Search Words Data Structure · Solution -LeetCode 271 - Encode and Decode Strings · Solution -LeetCode 304 - Range Sum Query 2D - Immutable · Solution -LeetCode 307 - Range Sum Query - Mutable · Solution -LeetCode 355 - Design Twitter · Solution -LeetCode 707 - Design Linked List · Solution -LeetCode 901 - Online Stock Span · Solution -LeetCode 981 - Time Based Key-Value Store · Solution -LeetCode 2013 - Detect Squares · Solution -LeetCode 2069 - Walking Robot Simulation II · Solution

Heap (12)¶

-LeetCode 215 - Kth Largest Element in an Array · Solution -LeetCode 253 - Meeting Rooms II · Solution -LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 621 - Task Scheduler · Solution -LeetCode 743 - Network Delay Time · Solution -LeetCode 787 - Cheapest Flights Within K Stops · Solution -LeetCode 973 - K Closest Points to Origin · Solution -LeetCode 1268 - Search Suggestions System · Solution -LeetCode 1438 - Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit · Solution -LeetCode 1631 - Path With Minimum Effort · Solution -LeetCode 1648 - Sell Diminishing-Valued Colored Balls · Solution -LeetCode 2333 - Minimum Sum of Squared Difference · Solution

Prefix Sum (11)¶

-LeetCode 209 - Minimum Size Subarray Sum · Solution -LeetCode 238 - Product of Array Except Self · Solution -LeetCode 253 - Meeting Rooms II · Solution -LeetCode 304 - Range Sum Query 2D - Immutable · Solution -LeetCode 523 - Continuous Subarray Sum · Solution -LeetCode 525 - Contiguous Array · Solution -LeetCode 560 - Subarray Sum Equals K · Solution -LeetCode 1094 - Car Pooling · Solution -LeetCode 1109 - Corporate Flight Bookings · Solution -LeetCode 1871 - Jump Game VII · Solution -LeetCode 2731 - Movement of Robots · Solution

Monotonic Stack (9)¶

-LeetCode 316 - Remove Duplicate Letters · Solution -LeetCode 402 - Remove K Digits · Solution -LeetCode 503 - Next Greater Element II · Solution -LeetCode 739 - Daily Temperatures · Solution -LeetCode 853 - Car Fleet · Solution -LeetCode 901 - Online Stock Span · Solution -LeetCode 907 - Sum of Subarray Minimums · Solution -LeetCode 2104 - Sum of Subarray Ranges · Solution -LeetCode 2289 - Steps to Make Array Non-decreasing · Solution

Linked List (9)¶

-LeetCode 2 - Add Two Numbers · Solution -LeetCode 19 - Remove Nth Node From End of List · Solution -LeetCode 92 - Reverse Linked List II · Solution -LeetCode 138 - Copy List with Random Pointer · Solution -LeetCode 142 - Linked List Cycle II · Solution -LeetCode 143 - Reorder List · Solution -LeetCode 146 - LRU Cache · Solution -LeetCode 355 - Design Twitter · Solution -LeetCode 2289 - Steps to Make Array Non-decreasing · Solution

Sliding Window (8)¶

-LeetCode 3 - Longest Substring Without Repeating Characters · Solution -LeetCode 209 - Minimum Size Subarray Sum · Solution -LeetCode 340 - Longest Substring with At Most K Distinct Characters · Solution -LeetCode 424 - Longest Repeating Character Replacement · Solution -LeetCode 438 - Find All Anagrams in a String · Solution -LeetCode 567 - Permutation in String · Solution -LeetCode 1438 - Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit · Solution -LeetCode 1871 - Jump Game VII · Solution

Tree (8)¶

-LeetCode 98 - Validate Binary Search Tree · Solution -LeetCode 102 - Binary Tree Level Order Traversal · Solution -LeetCode 105 - Construct Binary Tree from Preorder and Inorder Traversal · Solution -LeetCode 199 - Binary Tree Right Side View · Solution -LeetCode 230 - Kth Smallest Element in a BST · Solution -LeetCode 235 - Lowest Common Ancestor of a Binary Search Tree · Solution -LeetCode 337 - House Robber III · Solution -LeetCode 1448 - Count Good Nodes in Binary Tree · Solution

Binary Tree (7)¶

-LeetCode 102 - Binary Tree Level Order Traversal · Solution -LeetCode 105 - Construct Binary Tree from Preorder and Inorder Traversal · Solution -LeetCode 199 - Binary Tree Right Side View · Solution -LeetCode 230 - Kth Smallest Element in a BST · Solution -LeetCode 235 - Lowest Common Ancestor of a Binary Search Tree · Solution -LeetCode 337 - House Robber III · Solution -LeetCode 1448 - Count Good Nodes in Binary Tree · Solution

Dynamic Programming (6)¶

-LeetCode 1039 - Minimum Score Triangulation of Polygon -LeetCode 877 - Stone Game -LeetCode 486 - Predict the Winner -LeetCode 72 - Edit Distance · Solution -LeetCode 516 - Longest Palindromic Subsequence · Solution -LeetCode 1143 - Longest Common Subsequence · Solution

Counting (5)¶

-LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 621 - Task Scheduler · Solution -LeetCode 2013 - Detect Squares · Solution -LeetCode 2029 - Stone Game IX · Solution -LeetCode 2531 - Make Number of Distinct Characters Equal · Solution

Trie (5)¶

-LeetCode 139 - Word Break · Solution -LeetCode 208 - Implement Trie (Prefix Tree) · Solution(Prefix Tree) -LeetCode 211 - Design Add and Search Words Data Structure · Solution -LeetCode 648 - Replace Words · Solution -LeetCode 1268 - Search Suggestions System · Solution

Divide And Conquer (5)¶

-LeetCode 53 - Maximum Subarray · Solution -LeetCode 105 - Construct Binary Tree from Preorder and Inorder Traversal · Solution -LeetCode 215 - Kth Largest Element in an Array · Solution -LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 973 - K Closest Points to Origin · Solution

Bit Manipulation (4)¶

-LeetCode 29 - Divide Two Integers · Solution -LeetCode 78 - Subsets · Solution -LeetCode 90 - Subsets II · Solution -LeetCode 371 - Sum of Two Integers · Solution

Recursion (4)¶

-LeetCode 2 - Add Two Numbers · Solution -LeetCode 50 - Pow(x, n) · Solution(x, n) -LeetCode 143 - Reorder List · Solution -LeetCode 2550 - Count Collisions of Monkeys on a Polygon · Solution

Dfs (4)¶

-LeetCode 98 - Validate Binary Search Tree · Solution -LeetCode 261 - Graph Valid Tree · Solution -LeetCode 1448 - Count Good Nodes in Binary Tree · Solution -LeetCode 2556 - Disconnect Path in a Binary Matrix by at Most One Flip · Solution

Bfs (4)¶

-LeetCode 261 - Graph Valid Tree · Solution -LeetCode 322 - Coin Change · Solution -LeetCode 1448 - Count Good Nodes in Binary Tree · Solution -LeetCode 2556 - Disconnect Path in a Binary Matrix by at Most One Flip · Solution

Simulation (4)¶

-LeetCode 43 - Multiply Strings · Solution -LeetCode 54 - Spiral Matrix · Solution -LeetCode 1094 - Car Pooling · Solution -LeetCode 2069 - Walking Robot Simulation II · Solution

String (3)¶

-LeetCode 72 - Edit Distance · Solution -LeetCode 516 - Longest Palindromic Subsequence · Solution -LeetCode 1143 - Longest Common Subsequence · Solution

Topological Sort (3)¶

-LeetCode 207 - Course Schedule · Solution -LeetCode 210 - Course Schedule II · Solution -LeetCode 802 - Find Eventual Safe States · Solution

Quickselect (3)¶

-LeetCode 215 - Kth Largest Element in an Array · Solution -LeetCode 347 - Top K Frequent Elements · Solution -LeetCode 973 - K Closest Points to Origin · Solution

Binary Search Tree (3)¶

-LeetCode 98 - Validate Binary Search Tree · Solution -LeetCode 230 - Kth Smallest Element in a BST · Solution -LeetCode 235 - Lowest Common Ancestor of a Binary Search Tree · Solution

Array (3)¶

-LeetCode 1039 - Minimum Score Triangulation of Polygon -LeetCode 877 - Stone Game -LeetCode 486 - Predict the Winner

Binary-Search (2)¶

-LeetCode 1648 - Sell Diminishing-Valued Colored Balls · Solution -LeetCode 2332 - The Latest Time to Catch a Bus · Solution

Heap Priority Queue (2)¶

-LeetCode 355 - Design Twitter · Solution -LeetCode 1094 - Car Pooling · Solution

Enumeration (2)¶

-LeetCode 204 - Count Primes · Solution -LeetCode 2310 - Sum of Numbers With Units Digit K · Solution

Bitmask (2)¶

-LeetCode 2572 - Count the Number of Square-Free Subsets · Solution -LeetCode 2741 - Special Permutations · Solution

Shortest Path (2)¶

-LeetCode 743 - Network Delay Time · Solution -LeetCode 787 - Cheapest Flights Within K Stops · Solution

Geometry (2)¶

-LeetCode 973 - K Closest Points to Origin · Solution -LeetCode 2280 - Minimum Lines to Represent a Line Chart · Solution

Math (2)¶

-LeetCode 877 - Stone Game -LeetCode 486 - Predict the Winner

Game Theory (2)¶

-LeetCode 877 - Stone Game -LeetCode 486 - Predict the Winner

Queue (1)¶

-LeetCode 1438 - Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit · Solution

Monotonic Queue (1)¶

-LeetCode 1438 - Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit · Solution

Long-Division (1)¶

-LeetCode 166 - Fraction to Recurring Decimal

Cycle-Detection (1)¶

-LeetCode 166 - Fraction to Recurring Decimal

Number-Theory (1)¶

-LeetCode 166 - Fraction to Recurring Decimal

Two-Pointers (1)¶

-LeetCode 2332 - The Latest Time to Catch a Bus · Solution

Game-Theory (1)¶

-LeetCode 2029 - Stone Game IX · Solution

State-Space-Search (1)¶

-LeetCode 1654 - Minimum Jumps to Reach Home

Shortest-Path (1)¶

-LeetCode 1654 - Minimum Jumps to Reach Home

Graph-Traversal (1)¶

-LeetCode 1654 - Minimum Jumps to Reach Home

Number Theory (1)¶

-LeetCode 204 - Count Primes · Solution

Bucket Sort (1)¶

-LeetCode 347 - Top K Frequent Elements · Solution

Binary Indexed Tree (1)¶

-LeetCode 307 - Range Sum Query - Mutable · Solution

Segment Tree (1)¶

-LeetCode 307 - Range Sum Query - Mutable · Solution

Combinatorics (1)¶

-LeetCode 62 - Unique Paths · Solution

Brainteaser (1)¶

-LeetCode 2731 - Movement of Robots · Solution

Doubly Linked List (1)¶

-LeetCode 146 - LRU Cache · Solution

Linked-List (1)¶

-LeetCode 707 - Design Linked List · Solution

Dual-Hashmap (1)¶

-LeetCode 2671 - Frequency Tracker

Frequency-Counting (1)¶

-LeetCode 2671 - Frequency Tracker

Data Stream (1)¶

-LeetCode 901 - Online Stock Span · Solution

Dynamic-Programming (1)¶

-LeetCode 2741 - Special Permutations · Solution

Bit-Manipulation (1)¶

-LeetCode 2741 - Special Permutations · Solution

Minimum Spanning Tree (1)¶

-LeetCode 1584 - Min Cost to Connect All Points · Solution

Memoization (1)¶

-LeetCode 139 - Word Break · Solution

Recursion (1)¶

-LeetCode 486 - Predict the Winner

🔴 Hard (277 problems)¶

Array (32)¶

-LeetCode 4 - Median of Two Sorted Arrays · Solution -LeetCode 42 - Trapping Rain Water · Solution -LeetCode 51 - N-Queens · Solution -LeetCode 84 - Largest Rectangle in Histogram · Solution -LeetCode 85 - Maximal Rectangle · Solution -LeetCode 135 - Candy · Solution -LeetCode 149 - Max Points on a Line · Solution -LeetCode 212 - Word Search II · Solution -LeetCode 218 - The Skyline Problem · Solution -LeetCode 220 - Contains Duplicate III · Solution -LeetCode 239 - Sliding Window Maximum · Solution -LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 321 - Create Maximum Number · Solution -LeetCode 327 - Count of Range Sum · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 778 - Swim in Rising Water · Solution -LeetCode 805 - Split Array With Same Average · Solution -LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 1125 - Smallest Sufficient Team · Solution -LeetCode 1368 - Minimum Cost to Make at Least One Valid Path in a Grid · Solution -LeetCode 1499 - Max Value of Equation · Solution -LeetCode 1851 - Minimum Interval to Include Each Query · Solution -LeetCode 1923 - Longest Common Subpath · Solution -LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference · Solution -LeetCode 2281 - Sum of Total Strength of Wizards · Solution -LeetCode 2290 - Minimum Obstacle Removal to Reach Corner · Solution -LeetCode 2407 - Longest Increasing Subsequence II · Solution -LeetCode 2584 - Split the Array to Make Coprime Products · Solution -LeetCode 2612 - Minimum Reverse Operations · Solution -LeetCode 2617 - Minimum Number of Visited Cells in a Grid · Solution -LeetCode 2659 - Make Array Empty · Solution -LeetCode 2736 - Maximum Sum Queries · Solution

Dynamic Programming (14)¶

-LeetCode 42 - Trapping Rain Water · Solution -LeetCode 44 - Wildcard Matching -LeetCode 85 - Maximal Rectangle · Solution -LeetCode 115 - Distinct Subsequences · Solution -LeetCode 124 - Binary Tree Maximum Path Sum · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 805 - Split Array With Same Average · Solution -LeetCode 847 - Shortest Path Visiting All Nodes · Solution -LeetCode 968 - Binary Tree Cameras · Solution -LeetCode 1125 - Smallest Sufficient Team · Solution -LeetCode 1977 - Number of Ways to Separate Numbers · Solution -LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference · Solution -LeetCode 2407 - Longest Increasing Subsequence II · Solution -LeetCode 2617 - Minimum Number of Visited Cells in a Grid · Solution

String (12)¶

-LeetCode 44 - Wildcard Matching -LeetCode 65 - Valid Number · Solution -LeetCode 76 - Minimum Window Substring · Solution -LeetCode 115 - Distinct Subsequences · Solution -LeetCode 126 - Word Ladder II · Solution -LeetCode 127 - Word Ladder · Solution -LeetCode 212 - Word Search II · Solution -LeetCode 297 - Serialize and Deserialize Binary Tree · Solution -LeetCode 420 - Strong Password Checker · Solution -LeetCode 1977 - Number of Ways to Separate Numbers · Solution -LeetCode 2156 - Find Substring With Given Hash Value · Solution -LeetCode 2157 - Groups of Strings · Solution

Heap (9)¶

-LeetCode 23 - Merge k Sorted Lists · Solution -LeetCode 218 - The Skyline Problem · Solution -LeetCode 239 - Sliding Window Maximum · Solution -LeetCode 295 - Find Median from Data Stream · Solution -LeetCode 420 - Strong Password Checker · Solution -LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 1368 - Minimum Cost to Make at Least One Valid Path in a Grid · Solution -LeetCode 1499 - Max Value of Equation · Solution -LeetCode 2290 - Minimum Obstacle Removal to Reach Corner · Solution

Binary Search (9)¶

-LeetCode 4 - Median of Two Sorted Arrays · Solution -LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 327 - Count of Range Sum · Solution -LeetCode 778 - Swim in Rising Water · Solution -LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 1851 - Minimum Interval to Include Each Query · Solution -LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference · Solution -LeetCode 2286 - Booking Concert Tickets in Groups · Solution -LeetCode 2617 - Minimum Number of Visited Cells in a Grid · Solution

Stack (7)¶

-LeetCode 42 - Trapping Rain Water · Solution -LeetCode 84 - Largest Rectangle in Histogram · Solution -LeetCode 85 - Maximal Rectangle · Solution -LeetCode 321 - Create Maximum Number · Solution -LeetCode 2281 - Sum of Total Strength of Wizards · Solution -LeetCode 2617 - Minimum Number of Visited Cells in a Grid · Solution -LeetCode 2736 - Maximum Sum Queries · Solution

Graph (7)¶

-LeetCode 269 - Alien Dictionary · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 332 - Reconstruct Itinerary · Solution -LeetCode 847 - Shortest Path Visiting All Nodes · Solution -LeetCode 1203 - Sort Items by Groups Respecting Dependencies · Solution -LeetCode 1368 - Minimum Cost to Make at Least One Valid Path in a Grid · Solution -LeetCode 2290 - Minimum Obstacle Removal to Reach Corner · Solution

Segment Tree (7)¶

-LeetCode 218 - The Skyline Problem · Solution -LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 327 - Count of Range Sum · Solution -LeetCode 1622 - Fancy Sequence · Solution -LeetCode 2286 - Booking Concert Tickets in Groups · Solution -LeetCode 2407 - Longest Increasing Subsequence II · Solution -LeetCode 2617 - Minimum Number of Visited Cells in a Grid · Solution

Math (6)¶

-LeetCode 149 - Max Points on a Line · Solution -LeetCode 805 - Split Array With Same Average · Solution -LeetCode 887 - Super Egg Drop · Solution -LeetCode 1622 - Fancy Sequence · Solution -LeetCode 2117 - Abbreviating the Product of a Range · Solution -LeetCode 2584 - Split the Array to Make Coprime Products · Solution

Bfs (6)¶

-LeetCode 126 - Word Ladder II · Solution -LeetCode 269 - Alien Dictionary · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 778 - Swim in Rising Water · Solution -LeetCode 847 - Shortest Path Visiting All Nodes · Solution -LeetCode 2612 - Minimum Reverse Operations · Solution

Sliding Window (6)¶

-LeetCode 76 - Minimum Window Substring · Solution -LeetCode 220 - Contains Duplicate III · Solution -LeetCode 239 - Sliding Window Maximum · Solution -LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 1499 - Max Value of Equation · Solution -LeetCode 2156 - Find Substring With Given Hash Value · Solution

Matrix (6)¶

-LeetCode 85 - Maximal Rectangle · Solution -LeetCode 212 - Word Search II · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 778 - Swim in Rising Water · Solution -LeetCode 1368 - Minimum Cost to Make at Least One Valid Path in a Grid · Solution -LeetCode 2290 - Minimum Obstacle Removal to Reach Corner · Solution

Sorting (5)¶

-LeetCode 220 - Contains Duplicate III · Solution -LeetCode 295 - Find Median from Data Stream · Solution -LeetCode 1851 - Minimum Interval to Include Each Query · Solution -LeetCode 2659 - Make Array Empty · Solution -LeetCode 2736 - Maximum Sum Queries · Solution

Breadth First Search (5)¶

-LeetCode 127 - Word Ladder · Solution -LeetCode 297 - Serialize and Deserialize Binary Tree · Solution -LeetCode 1203 - Sort Items by Groups Respecting Dependencies · Solution -LeetCode 1368 - Minimum Cost to Make at Least One Valid Path in a Grid · Solution -LeetCode 2290 - Minimum Obstacle Removal to Reach Corner · Solution

Divide And Conquer (5)¶

-LeetCode 4 - Median of Two Sorted Arrays · Solution -LeetCode 23 - Merge k Sorted Lists · Solution -LeetCode 218 - The Skyline Problem · Solution -LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 327 - Count of Range Sum · Solution

Ordered Set (5)¶

-LeetCode 218 - The Skyline Problem · Solution -LeetCode 220 - Contains Duplicate III · Solution -LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 327 - Count of Range Sum · Solution -LeetCode 2612 - Minimum Reverse Operations · Solution

Monotonic Stack (5)¶

-LeetCode 42 - Trapping Rain Water · Solution -LeetCode 84 - Largest Rectangle in Histogram · Solution -LeetCode 85 - Maximal Rectangle · Solution -LeetCode 321 - Create Maximum Number · Solution -LeetCode 2281 - Sum of Total Strength of Wizards · Solution

Dynamic Programming (5)¶

-LeetCode 1547 - Minimum Cost to Cut a Stick -LeetCode 312 - Burst Balloons -LeetCode 1406 - Stone Game III -LeetCode 664 - Strange Printer -LeetCode 10 - Regular Expression Matching · Solution

Greedy (5)¶

-LeetCode 44 - Wildcard Matching -LeetCode 135 - Candy · Solution -LeetCode 321 - Create Maximum Number · Solution -LeetCode 420 - Strong Password Checker · Solution -LeetCode 2659 - Make Array Empty · Solution

Two Pointers (4)¶

-LeetCode 42 - Trapping Rain Water · Solution -LeetCode 295 - Find Median from Data Stream · Solution -LeetCode 321 - Create Maximum Number · Solution -LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference · Solution

Design (4)¶

-LeetCode 295 - Find Median from Data Stream · Solution -LeetCode 297 - Serialize and Deserialize Binary Tree · Solution -LeetCode 1622 - Fancy Sequence · Solution -LeetCode 2286 - Booking Concert Tickets in Groups · Solution

Depth First Search (4)¶

-LeetCode 124 - Binary Tree Maximum Path Sum · Solution -LeetCode 297 - Serialize and Deserialize Binary Tree · Solution -LeetCode 968 - Binary Tree Cameras · Solution -LeetCode 1203 - Sort Items by Groups Respecting Dependencies · Solution

Bit Manipulation (4)¶

-LeetCode 847 - Shortest Path Visiting All Nodes · Solution -LeetCode 1125 - Smallest Sufficient Team · Solution -LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference · Solution -LeetCode 2157 - Groups of Strings · Solution

Hash Table (4)¶

-LeetCode 76 - Minimum Window Substring · Solution -LeetCode 126 - Word Ladder II · Solution -LeetCode 127 - Word Ladder · Solution -LeetCode 2584 - Split the Array to Make Coprime Products · Solution

Binary Indexed Tree (4)¶

-LeetCode 218 - The Skyline Problem · Solution -LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 327 - Count of Range Sum · Solution -LeetCode 2286 - Booking Concert Tickets in Groups · Solution

Backtracking (4)¶

-LeetCode 51 - N-Queens · Solution -LeetCode 52 - N-Queens II · Solution -LeetCode 126 - Word Ladder II · Solution -LeetCode 212 - Word Search II · Solution

Dfs (4)¶

-LeetCode 269 - Alien Dictionary · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 332 - Reconstruct Itinerary · Solution -LeetCode 778 - Swim in Rising Water · Solution

String (4)¶

-LeetCode 1392 - Longest Happy Prefix -LeetCode 664 - Strange Printer -LeetCode 214 - Shortest Palindrome -LeetCode 10 - Regular Expression Matching · Solution

Binary-Search (3)¶

-LeetCode 887 - Super Egg Drop · Solution -LeetCode 1923 - Longest Common Subpath · Solution -LeetCode 2736 - Maximum Sum Queries · Solution

Topological Sort (3)¶

-LeetCode 269 - Alien Dictionary · Solution -LeetCode 329 - Longest Increasing Path in a Matrix · Solution -LeetCode 1203 - Sort Items by Groups Respecting Dependencies · Solution

Bitmask (3)¶

-LeetCode 805 - Split Array With Same Average · Solution -LeetCode 1125 - Smallest Sufficient Team · Solution -LeetCode 2035 - Partition Array Into Two Arrays to Minimize Sum Difference · Solution

Array (3)¶

-LeetCode 1547 - Minimum Cost to Cut a Stick -LeetCode 312 - Burst Balloons -LeetCode 1406 - Stone Game III

Union Find (3)¶

-LeetCode 778 - Swim in Rising Water · Solution -LeetCode 2157 - Groups of Strings · Solution -LeetCode 2617 - Minimum Number of Visited Cells in a Grid · Solution

Queue (3)¶

-LeetCode 239 - Sliding Window Maximum · Solution -LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 1499 - Max Value of Equation · Solution

Monotonic Queue (3)¶

-LeetCode 239 - Sliding Window Maximum · Solution -LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 1499 - Max Value of Equation · Solution

Tree (3)¶

-LeetCode 124 - Binary Tree Maximum Path Sum · Solution -LeetCode 297 - Serialize and Deserialize Binary Tree · Solution -LeetCode 968 - Binary Tree Cameras · Solution

Binary Tree (3)¶

-LeetCode 124 - Binary Tree Maximum Path Sum · Solution -LeetCode 297 - Serialize and Deserialize Binary Tree · Solution -LeetCode 968 - Binary Tree Cameras · Solution

Line Sweep (2)¶

-LeetCode 218 - The Skyline Problem · Solution -LeetCode 1851 - Minimum Interval to Include Each Query · Solution

Prefix Sum (2)¶

-LeetCode 862 - Shortest Subarray with Sum at Least K · Solution -LeetCode 2281 - Sum of Total Strength of Wizards · Solution

Rolling Hash (2)¶

-LeetCode 1392 - Longest Happy Prefix -LeetCode 214 - Shortest Palindrome

String Matching (2)¶

-LeetCode 1392 - Longest Happy Prefix -LeetCode 214 - Shortest Palindrome

Hash Function (2)¶

-LeetCode 1392 - Longest Happy Prefix -LeetCode 214 - Shortest Palindrome

Heap Priority Queue (2)¶

-LeetCode 778 - Swim in Rising Water · Solution -LeetCode 1851 - Minimum Interval to Include Each Query · Solution

Merge Sort (2)¶

-LeetCode 315 - Count of Smaller Numbers After Self · Solution -LeetCode 327 - Count of Range Sum · Solution

Shortest Path (2)¶

-LeetCode 1368 - Minimum Cost to Make at Least One Valid Path in a Grid · Solution -LeetCode 2290 - Minimum Obstacle Removal to Reach Corner · Solution

Memoization (2)¶

-LeetCode 488 - Zuma Game -LeetCode 329 - Longest Increasing Path in a Matrix · Solution

Linked List (2)¶

-LeetCode 23 - Merge k Sorted Lists · Solution -LeetCode 25 - Reverse Nodes in k-Group · Solution

Recursion (2)¶

-LeetCode 25 - Reverse Nodes in k-Group · Solution -LeetCode 44 - Wildcard Matching

Two-Pointers (1)¶

-LeetCode 2234 - Maximum Total Beauty of the Gardens

Prefix-Sum (1)¶

-LeetCode 2234 - Maximum Total Beauty of the Gardens

Optimization (1)¶

-LeetCode 2234 - Maximum Total Beauty of the Gardens

Segment-Tree (1)¶

-LeetCode 2736 - Maximum Sum Queries · Solution

Monotonic-Stack (1)¶

-LeetCode 2736 - Maximum Sum Queries · Solution

Data Stream (1)¶

-LeetCode 295 - Find Median from Data Stream · Solution

Number Theory (1)¶

-LeetCode 2584 - Split the Array to Make Coprime Products · Solution

Eulerian Circuit (1)¶

-LeetCode 332 - Reconstruct Itinerary · Solution

Gcd (1)¶

-LeetCode 2183 - Count Array Pairs Divisible by K

Divisor-Counting (1)¶

-LeetCode 2183 - Count Array Pairs Divisible by K

Pair-Counting (1)¶

-LeetCode 2183 - Count Array Pairs Divisible by K

Sorting (1)¶

-LeetCode 1547 - Minimum Cost to Cut a Stick

Bitmask-Dp (1)¶

-LeetCode 1494 - Parallel Courses II

Subset-Enumeration (1)¶

-LeetCode 1494 - Parallel Courses II

Dag-Scheduling (1)¶

-LeetCode 1494 - Parallel Courses II

Recursion (1)¶

-LeetCode 10 - Regular Expression Matching · Solution

Lazy-Propagation (1)¶

-LeetCode 2569 - Handling Sum Queries After Update

Range-Update (1)¶

-LeetCode 2569 - Handling Sum Queries After Update

Toggle-Operation (1)¶

-LeetCode 2569 - Handling Sum Queries After Update

Trie (1)¶

-LeetCode 212 - Word Search II · Solution

Bucket Sort (1)¶

-LeetCode 220 - Contains Duplicate III · Solution

Math (1)¶

-LeetCode 1406 - Stone Game III

Game Theory (1)¶

-LeetCode 1406 - Stone Game III

Game-Simulation (1)¶

-LeetCode 488 - Zuma Game

State-Search (1)¶

-LeetCode 488 - Zuma Game

Frequency-Count (1)¶

-LeetCode 1862 - Sum of Floored Pairs

Harmonic-Series (1)¶

-LeetCode 1862 - Sum of Floored Pairs

Counting (1)¶

-LeetCode 1862 - Sum of Floored Pairs

Dynamic-Programming (1)¶

-LeetCode 887 - Super Egg Drop · Solution

Rolling-Hash (1)¶

-LeetCode 1923 - Longest Common Subpath · Solution

Hash-Function (1)¶

-LeetCode 1923 - Longest Common Subpath · Solution

Suffix-Array (1)¶

-LeetCode 1923 - Longest Common Subpath · Solution

Suffix Array (1)¶

-LeetCode 1977 - Number of Ways to Separate Numbers · Solution

Hash-Table (1)¶

-LeetCode 149 - Max Points on a Line · Solution

Geometry (1)¶

-LeetCode 149 - Max Points on a Line · Solution

Rolling Hash (1)¶

-LeetCode 2156 - Find Substring With Given Hash Value · Solution