Hash Table LeetCode Questions Asked in Microsoft Interviews
Hash Table is one of the most important data structures used in Microsoft software engineering interviews. It allows efficient O(1) average time complexity for lookup, insertion, and deletion operations.
Many interview questions test your ability to use hash tables for frequency counting, fast lookups, and optimizing brute-force solutions.
In this guide, we have compiled some of the most frequently asked Hash Table problems reported in Microsoft interviews. Each question includes its difficulty level, interview frequency, and a direct link to the LeetCode problem so that you can start practicing immediately.
Below is a curated list of Hash Table LeetCode questions asked in Microsoft interviews.
| Sl.No | Question | Difficulty | Frequency | LeetCode Link |
|---|
| 1 | Time Based Key-Value Store | MEDIUM | 100.00% | Solve |
| 2 | Two Sum | EASY | 100.00% | Solve |
| 3 | Longest Substring Without Repeating Characters | MEDIUM | 82.60% | Solve |
| 4 | LRU Cache | MEDIUM | 79.20% | Solve |
| 5 | Group Anagrams | MEDIUM | 78.90% | Solve |
| 6 | Bulls and Cows | MEDIUM | 77.30% | Solve |
| 7 | Letter Combinations of a Phone Number | MEDIUM | 68.20% | Solve |
| 8 | Longest Consecutive Sequence | MEDIUM | 66.20% | Solve |
| 9 | Roman to Integer | EASY | 66.10% | Solve |
| 10 | Subarray Sum Equals K | MEDIUM | 62.00% | Solve |
| 11 | Valid Sudoku | MEDIUM | 61.10% | Solve |
| 12 | Word Break | MEDIUM | 60.60% | Solve |
| 13 | Majority Element | EASY | 59.50% | Solve |
| 14 | First Missing Positive | HARD | 59.10% | Solve |
| 15 | Set Matrix Zeroes | MEDIUM | 58.70% | Solve |
| 16 | Reorganize String | MEDIUM | 58.00% | Solve |
| 17 | Minimum Window Substring | HARD | 54.80% | Solve |
| 18 | Word Break II | HARD | 53.30% | Solve |
| 19 | Top K Frequent Elements | MEDIUM | 53.00% | Solve |
| 20 | Integer to Roman | MEDIUM | 52.20% | Solve |
| 21 | Valid Anagram | EASY | 51.40% | Solve |
| 22 | Happy Number | EASY | 46.70% | Solve |
| 23 | LFU Cache | HARD | 46.70% | Solve |
| 24 | Word Ladder | HARD | 44.80% | Solve |
| 25 | Isomorphic Strings | EASY | 43.10% | Solve |
| 26 | Sudoku Solver | HARD | 42.70% | Solve |
| 27 | Contains Duplicate II | EASY | 42.20% | Solve |
| 28 | Missing Number | EASY | 42.20% | Solve |
| 29 | Copy List with Random Pointer | MEDIUM | 39.20% | Solve |
| 30 | Clone Graph | MEDIUM | 38.60% | Solve |
| 31 | Number of Islands II | HARD | 38.60% | Solve |
| 32 | Intersection of Two Arrays | EASY | 37.90% | Solve |
| 33 | First Unique Character in a String | EASY | 37.90% | Solve |
| 34 | Maximum Frequency Stack | HARD | 37.90% | Solve |
| 35 | Linked List Cycle | EASY | 35.20% | Solve |
| 36 | Construct Binary Tree from Preorder and Inorder Traversal | MEDIUM | 33.60% | Solve |
| 37 | Substring with Concatenation of All Words | HARD | 32.60% | Solve |
| 38 | Fraction to Recurring Decimal | MEDIUM | 30.60% | Solve |
| 39 | Longest Substring with At Most Two Distinct Characters | MEDIUM | 25.10% | Solve |
| 40 | Palindrome Permutation | EASY | 22.30% | Solve |
| 41 | Word Pattern | EASY | 19.00% | Solve |
| 42 | Construct Binary Tree from Inorder and Postorder Traversal | MEDIUM | 17.40% | Solve |
| 43 | All Nodes Distance K in Binary Tree | MEDIUM | 2.86% | Solve |
| 44 | Number of Distinct Islands | MEDIUM | 2.84% | Solve |
| 45 | Implement Trie (Prefix Tree) | MEDIUM | 2.65% | Solve |
| 46 | Encode and Decode TinyURL | MEDIUM | 2.65% | Solve |
| 47 | Find All Anagrams in a String | MEDIUM | 2.57% | Solve |
| 48 | Binary Tree Vertical Order Traversal | MEDIUM | 2.55% | Solve |
| 49 | Design Hit Counter | MEDIUM | 2.33% | Solve |
| 50 | Max Points on a Line | HARD | 2.11% | Solve |
You can also track your progress and practice these questions using our tool:
Microsoft LeetCode Interview Questions Tracker
How to Prepare for Hash Table Questions in Microsoft Interviews
To perform well in Microsoft coding interviews, it’s important to understand how and when to use hash tables effectively.
Some useful preparation strategies include:
- Practicing frequency count problems (maps/dictionaries)
- Solving problems involving duplicate detection and lookups
- Combining hash tables with two pointers or sliding window techniques
- Understanding time vs space trade-offs
- Optimizing brute-force solutions using hashing
Strong command over hash tables can drastically improve your problem-solving speed and efficiency.
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