Boost your Data Structures and Algorithms expertise with our diverse problem sets. Perfect for interview prep and competitive programming.
All Hash Table Problems
- Two Sum
- Longest Substring Without Repeating Characters
- Integer to Roman
- Roman to Integer
- Letter Combinations of a Phone Number
- Substring with Concatenation of All Words
- Valid Sudoku
- Sudoku Solver
- First Missing Positive
- Group Anagrams
- Set Matrix Zeroes
- Minimum Window Substring
- Construct Binary Tree from Preorder and Inorder Traversal
- Construct Binary Tree from Inorder and Postorder Traversal
- Word Ladder II
- Word Ladder
- Longest Consecutive Sequence
- Clone Graph
- Copy List with Random Pointer
- Word Break
- Word Break II
- Linked List Cycle
- Linked List Cycle II
- LRU Cache
- Max Points on a Line
- Longest Substring with At Most Two Distinct Characters
- Intersection of Two Linked Lists
- Fraction to Recurring Decimal
- Majority Element
- Two Sum III – Data structure design
- Repeated DNA Sequences
- Happy Number
- Isomorphic Strings
- Implement Trie (Prefix Tree)
- Contains Duplicate
- Contains Duplicate II
- Majority Element II
- Valid Anagram
- Shortest Word Distance II
- Strobogrammatic Number
- Group Shifted Strings
- Ugly Number II
- Palindrome Permutation
- Palindrome Permutation II
- Missing Number
- Unique Word Abbreviation
- Word Pattern
- Word Pattern II
- Bulls and Cows
- Number of Islands II
- Sparse Matrix Multiplication
- Binary Tree Vertical Order Traversal
- Maximum Size Subarray Sum Equals k
- Palindrome Pairs
- Longest Substring with At Most K Distinct Characters
- Top K Frequent Elements
- Design Tic-Tac-Toe
- Intersection of Two Arrays
- Intersection of Two Arrays II
- Design Snake Game
- Design Twitter
- Line Reflection
- Rearrange String k Distance Apart
- Logger Rate Limiter
- Design Phone Directory
- Insert Delete GetRandom O(1)
- Insert Delete GetRandom O(1) – Duplicates allowed
- Ransom Note
- First Unique Character in a String
- Find the Difference
- Longest Substring with At Least K Repeating Characters
- Random Pick Index
- Longest Palindrome
- Maximum XOR of Two Numbers in an Array
- Reconstruct Original Digits from English
- Longest Repeating Character Replacement
- All O`one Data Structure
- Minimum Genetic Mutation
- Find All Anagrams in a String
- Find All Duplicates in an Array
- Number of Boomerangs
- Find All Numbers Disappeared in an Array
- Sort Characters By Frequency
- 4Sum II
- Circular Array Loop
- LFU Cache
- Sliding Window Median
- Non-decreasing Subsequences
- Next Greater Element I
- Keyboard Row
- Most Frequent Subtree Sum
- Random Flip Matrix
- Longest Uncommon Subsequence II
- Continuous Subarray Sum
- Contiguous Array
- Lonely Pixel I
- K-diff Pairs in an Array
- Lonely Pixel II
- Encode and Decode TinyURL
- Split Array with Equal Sum