AI Mobile CodersDSA Practice for Mobile Developers
Sharpen the data structures & algorithms that Android and iOS interviews actually test — hand-picked from real questions asked at Google, Meta, Amazon and other top product companies. Solve, track your progress, and get interview-ready.
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Arrays & Hashing
9 problems| Contains Duplicate | Easy | |
| Valid Anagram | Easy | |
| Two Sum | Easy | |
| Group Anagrams | Medium | |
| Top K Frequent Elements | Medium | |
| Product of Array Except Self | Medium | |
| Valid Sudoku | Medium | |
| Encode and Decode Strings | Medium | |
| Longest Consecutive Sequence | Medium |
Two Pointers
5 problems| Valid Palindrome | Easy | |
| Two Sum II Input Array Is Sorted | Medium | |
| 3Sum | Medium | |
| Container With Most Water | Medium | |
| Trapping Rain Water | Hard |
Sliding Window
6 problemsStack
7 problems| Valid Parentheses | Easy | |
| Min Stack | Medium | |
| Evaluate Reverse Polish Notation | Medium | |
| Generate Parentheses | Medium | |
| Daily Temperatures | Medium | |
| Car Fleet | Medium | |
| Largest Rectangle In Histogram | Hard |
Binary Search
7 problems| Binary Search | Easy | |
| Search a 2D Matrix | Medium | |
| Koko Eating Bananas | Medium | |
| Find Minimum In Rotated Sorted Array | Medium | |
| Search In Rotated Sorted Array | Medium | |
| Time Based Key Value Store | Medium | |
| Median of Two Sorted Arrays | Hard |
Linked List
11 problems| Reverse Linked List | Easy | |
| Merge Two Sorted Lists | Easy | |
| Reorder List | Medium | |
| Remove Nth Node From End of List | Medium | |
| Copy List With Random Pointer | Medium | |
| Add Two Numbers | Medium | |
| Linked List Cycle | Easy | |
| Find The Duplicate Number | Medium | |
| LRU Cache | Medium | |
| Merge K Sorted Lists | Hard | |
| Reverse Nodes In K Group | Hard |
Trees
15 problemsTries
3 problems| Implement Trie Prefix Tree | Medium | |
| Design Add And Search Words Data Structure | Medium | |
| Word Search II | Hard |
Heap / Priority Queue
7 problems| Kth Largest Element In a Stream | Easy | |
| Last Stone Weight | Easy | |
| K Closest Points to Origin | Medium | |
| Kth Largest Element In An Array | Medium | |
| Task Scheduler | Medium | |
| Design Twitter | Medium | |
| Find Median From Data Stream | Hard |
Backtracking
9 problems| Subsets | Medium | |
| Combination Sum | Medium | |
| Permutations | Medium | |
| Subsets II | Medium | |
| Combination Sum II | Medium | |
| Word Search | Medium | |
| Palindrome Partitioning | Medium | |
| Letter Combinations of a Phone Number | Medium | |
| N Queens | Hard |
Graphs
13 problems| Number of Islands | Medium | |
| Clone Graph | Medium | |
| Max Area of Island | Medium | |
| Pacific Atlantic Water Flow | Medium | |
| Surrounded Regions | Medium | |
| Rotting Oranges | Medium | |
| Walls And Gates | Medium | |
| Course Schedule | Medium | |
| Course Schedule II | Medium | |
| Redundant Connection | Medium | |
| Number of Connected Components In An Undirected Graph | Medium | |
| Graph Valid Tree | Medium | |
| Word Ladder | Hard |
Advanced Graphs
6 problems| Reconstruct Itinerary | Hard | |
| Min Cost to Connect Points | Medium | |
| Network Delay Time | Medium | |
| Swim In Rising Water | Hard | |
| Alien Dictionary | Hard | |
| Cheapest Flights Within K Stops | Medium |
1-D Dynamic Programming
12 problems| Climbing Stairs | Easy | |
| Min Cost Climbing Stairs | Easy | |
| House Robber | Medium | |
| House Robber II | Medium | |
| Longest Palindromic Substring | Medium | |
| Palindromic Substrings | Medium | |
| Decode Ways | Medium | |
| Coin Change | Medium | |
| Maximum Product Subarray | Medium | |
| Word Break | Medium | |
| Longest Increasing Subsequence | Medium | |
| Partition Equal Subset Sum | Medium |
2-D Dynamic Programming
11 problems| Unique Paths | Medium | |
| Longest Common Subsequence | Medium | |
| Best Time to Buy And Sell Stock With Cooldown | Medium | |
| Coin Change II | Medium | |
| Target Sum | Medium | |
| Interleaving String | Medium | |
| Longest Increasing Path In a Matrix | Hard | |
| Distinct Subsequences | Hard | |
| Edit Distance | Medium | |
| Burst Balloons | Hard | |
| Regular Expression Matching | Hard |
Greedy
8 problems| Maximum Subarray | Medium | |
| Jump Game | Medium | |
| Jump Game II | Medium | |
| Gas Station | Medium | |
| Hand of Straights | Medium | |
| Merge Triplets to Form Target Triplet | Medium | |
| Partition Labels | Medium | |
| Valid Parenthesis String | Medium |
Intervals
6 problems| Insert Interval | Medium | |
| Merge Intervals | Medium | |
| Non Overlapping Intervals | Medium | |
| Meeting Rooms | Easy | |
| Meeting Rooms II | Medium | |
| Minimum Interval to Include Each Query | Hard |
Math & Geometry
8 problems| Rotate Image | Medium | |
| Spiral Matrix | Medium | |
| Set Matrix Zeroes | Medium | |
| Happy Number | Easy | |
| Plus One | Easy | |
| Pow(x, n) | Medium | |
| Multiply Strings | Medium | |
| Detect Squares | Medium |
Bit Manipulation
7 problems| Single Number | Easy | |
| Number of 1 Bits | Easy | |
| Counting Bits | Easy | |
| Reverse Bits | Easy | |
| Missing Number | Easy | |
| Sum of Two Integers | Medium | |
| Reverse Integer | Medium |