Ace Coding Interview with 75 Qs
- 75 Essential & Trending Problems
- Must-do problem list for interview prep
- Best for 1~3 month of prep time
| Problem | Difficulty | Tags |
|---|---|---|
| Array / String | ||
| Merge Strings Alternately | Easy | # 1768, Two Pointers, String |
| Greatest Common Divisor of Strings | Easy | # 1071, Math, String |
| Kids With the Greatest Number of Candies | Easy | # 1431, Array |
| Can Place Flowers | Easy | # 605, Array, Greedy |
| Reverse Vowels of a String | Easy | # 345, Two Pointers, String |
| Reverse Words in a String | Medium | # 151, Two Pointers, String |
| Product of Array Except Self | Medium | # 238, Array, Prefix Sum |
| Increasing Triplet Subsequence | Medium | # 334, Array, Greedy |
| String Compression | Medium | # 443, Two Pointers, String |
| Two Pointers | ||
| Move Zeroes | Easy | # 283, Array, Two Pointers |
| Is Subsequence | Easy | # 392, Two Pointers, String, Dynamic Programming |
| Container With Most Water | Medium | # 11, Array, Two Pointers, Greedy |
| Max Number of K-Sum Pairs | Medium | # 1679, Array, Hash Table, Two Pointers, Sorting |
| Sliding Window | ||
| Maximum Average Subarray I | Easy | # 643, Array, Sliding Window |
| Maximum Number of Vowels in a Substring of Given Length | Medium | # 1456, String, Sliding Window |
| Max Consecutive Ones III | Medium | # 1004, Array, Binary Search, Sliding Window, Prefix Sum |
| Longest Subarray of 1's After Deleting One Element | Medium | # 1493, Array, Dynamic Programming, Sliding Window |
| Prefix Sum | ||
| Find the Highest Altitude | Easy | # 1732, Array, Prefix Sum |
| Find Pivot Index | Easy | # 724, Array, Prefix Sum |
| Hash Map / Set | ||
| Find the Difference of Two Arrays | Easy | # 2215, Array, Hash Table |
| Unique Number of Occurrences | Easy | # 1207, Array, Hash Table |
| Determine if Two Strings Are Close | Medium | # 1657, Hash Table, String, Sorting, Counting |
| Equal Row and Column Pairs | Medium | # 2352, Array, Hash Table, Matrix, Simulation |
| Stack | ||
| Removing Stars From a String | Medium | # 2390, String, Stack, Simulation |
| Asteroid Collision | Medium | # 735, Array, Stack, Simulation |
| Decode String | Medium | # 394, String, Stack, Recursion |
| Queue | ||
| Number of Recent Calls | Easy | # 933, Design, Queue, Data Stream |
| Dota2 Senate | Medium | # 649, String, Greedy, Queue |
| Linked List | ||
| Delete the Middle Node of a Linked List | Medium | # 2095, Linked List, Two Pointers |
| Odd Even Linked List | Medium | # 328, Linked List |
| Reverse Linked List | Easy | # 206, Linked List, Recursion |
| Maximum Twin Sum of a Linked List | Medium | # 2130, Linked List, Two Pointers, Stack |
| Binary Tree - DFS | ||
| Maximum Depth of Binary Tree | Easy | # 104, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
| Leaf-Similar Trees | Easy | # 872, Tree, Depth-First Search, Binary Tree |
| Count Good Nodes in Binary Tree | Medium | # 1448, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
| Path Sum III | Medium | # 437, Tree, Depth-First Search, Binary Tree |
| Longest ZigZag Path in a Binary Tree | Medium | # 1372, Dynamic Programming, Tree, Depth-First Search, Binary Tree |
| Lowest Common Ancestor of a Binary Tree | Medium | # 236, Tree, Depth-First Search, Binary Tree |
| Binary Tree - BFS | ||
| Binary Tree Right Side View | Medium | # 199, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
| Maximum Level Sum of a Binary Tree | Medium | # 1161, Tree, Depth-First Search, Breadth-First Search, Binary Tree |
| Binary Search Tree | ||
| Search in a Binary Search Tree | Easy | # 700, Tree, Binary Search Tree, Binary Tree |
| Delete Node in a BST | Medium | # 450, Tree, Binary Search Tree, Binary Tree |
| Graphs - DFS | ||
| Keys and Rooms | Medium | # 841, Depth-First Search, Breadth-First Search, Graph |
| Number of Provinces | Medium | # 547, Depth-First Search, Breadth-First Search, Union Find, Graph |
| Reorder Routes to Make All Paths Lead to the City Zero | Medium | # 1466, Depth-First Search, Breadth-First Search, Graph |
| Evaluate Division | Medium | # 399, Array, Depth-First Search, Breadth-First Search, Union Find, Graph, Shortest Path |
| Graphs - BFS | ||
| Nearest Exit from Entrance in Maze | Medium | # 1926, Array, Breadth-First Search, Matrix |
| Rotting Oranges | Medium | # 994, Array, Breadth-First Search, Matrix |
| Heap / Priority Queue | ||
| Kth Largest Element in an Array | Medium | # 215, Array, Divide and Conquer, Sorting, Heap (Priority Queue), Quickselect |
| Smallest Number in Infinite Set | Medium | # 2336, Hash Table, Design, Heap (Priority Queue) |
| Maximum Subsequence Score | Medium | # 2542, Array, Greedy, Sorting, Heap (Priority Queue) |
| Total Cost to Hire K Workers | Medium | # 2462, Array, Two Pointers, Heap (Priority Queue), Simulation |
| Binary Search | ||
| Guess Number Higher or Lower | Easy | # 374, Binary Search, Interactive |
| Successful Pairs of Spells and Potions | Medium | # 2300, Array, Two Pointers, Binary Search, Sorting |
| Find Peak Element | Medium | # 162, Array, Binary Search |
| Koko Eating Bananas | Medium | # 875, Array, Binary Search |
| Backtracking | ||
| Letter Combinations of a Phone Number | Medium | # 17, Hash Table, String, Backtracking |
| Combination Sum III | Medium | # 216, Array, Backtracking |
| DP - 1D | ||
| N-th Tribonacci Number | Easy | # 1137, Math, Dynamic Programming, Memoization |
| Min Cost Climbing Stairs | Easy | # 746, Array, Dynamic Programming |
| House Robber | Medium | # 198, Array, Dynamic Programming |
| Domino and Tromino Tiling | Medium | # 790, Dynamic Programming |
| DP - Multidimensional | ||
| Unique Paths | Medium | # 62, Math, Dynamic Programming, Combinatorics |
| Longest Common Subsequence | Medium | # 1143, String, Dynamic Programming |
| Best Time to Buy and Sell Stock with Transaction Fee | Medium | # 714, Array, Dynamic Programming, Greedy |
| Edit Distance | Medium | # 72, String, Dynamic Programming |
| Bit Manipulation | ||
| Counting Bits | Easy | # 338, Dynamic Programming, Bit Manipulation |
| Single Number | Easy | # 136, Array, Bit Manipulation |
| Minimum Flips to Make a OR b Equal to c | Medium | # 1318, Bit Manipulation |
| Trie | ||
| Implement Trie (Prefix Tree) | Medium | # 208, Hash Table, String, Design, Trie |
| Search Suggestions System | Medium | # 1268, Array, String, Binary Search, Trie, Sorting, Heap (Prefix Tree) |
| Intervals | ||
| Non-overlapping Intervals | Medium | # 435, Array, Dynamic Programming, Greedy, Sorting |
| Minimum Number of Arrows to Burst Balloons | Medium | # 452, Array, Greedy, Sorting |
| Monotonic Stack | ||
| Daily Temperatures | Medium | # 739, Array, Stack, Monotonic Stack |
| Online Stock Span | Medium | # 901, Stack, Design, Monotonic Stack, Data Stream |