Cisco LeetCode Questions
87 questions all-time · 24 easy · 50 medium · 13 hard
| # | Problem | Difficulty | Frequency | Acceptance |
|---|---|---|---|---|
| 1 | Longest Palindromic Substring Two Pointers, String, Dynamic Programming | Medium | 100 | 35.8% |
| 2 | Predict the Winner Array, Math, Dynamic Programming, Recursion, Game Theory | Medium | 98 | 55.7% |
| 3 | House Robber Array, Dynamic Programming | Medium | 98 | 52.3% |
| 4 | Lucky Numbers in a Matrix Array, Matrix | Easy | 85 | 79.9% |
| 5 | Rotate Image Array, Math, Matrix | Medium | 85 | 77.9% |
| 6 | Spiral Matrix Array, Matrix, Simulation | Medium | 84 | 53.9% |
| 7 | Fizz Buzz Math, String, Simulation | Easy | 70 | 74.4% |
| 8 | LRU Cache Hash Table, Linked List, Design, Doubly-Linked List | Medium | 67 | 45.2% |
| 9 | Snakes and Ladders Array, Breadth-First Search, Matrix | Medium | 67 | 47.8% |
| 10 | Number of Valid Words in a Sentence String | Easy | 67 | 30.0% |
| 11 | Find Third Transaction Database | Medium | 65 | 53.9% |
| 12 | Maximum Difference Between Increasing Elements Array | Easy | 65 | 66.1% |
| 13 | Merge Intervals Array, Sorting | Medium | 65 | 49.4% |
| 14 | Maximum Subarray Array, Divide and Conquer, Dynamic Programming | Medium | 63 | 52.1% |
| 15 | Implement Router Array, Hash Table, Binary Search, Design, Queue, Ordered Set | Medium | 63 | 21.8% |
| 16 | Find the Largest Area of Square Inside Two Rectangles Array, Math, Geometry | Medium | 63 | 45.1% |
| 17 | Minimum Cost to Make Array Equal Array, Binary Search, Greedy, Sorting, Prefix Sum | Hard | 63 | 46.3% |
| 18 | Word Search II Array, String, Backtracking, Trie, Matrix | Hard | 63 | 37.3% |
| 19 | Number of Equal Count Substrings Hash Table, String, Sliding Window, Counting | Medium | 63 | 44.7% |
| 20 | Sum of k-Mirror Numbers Math, Enumeration | Hard | 63 | 42.0% |
| 21 | Check if Binary String Has at Most One Segment of Ones String | Easy | 63 | 39.0% |
| 22 | Max Points on a Line Array, Hash Table, Math, Geometry | Hard | 59 | 29.0% |
| 23 | Happy Number Hash Table, Math, Two Pointers | Easy | 59 | 58.1% |
| 24 | Stone Game Array, Math, Dynamic Programming, Game Theory | Medium | 59 | 71.6% |
| 25 | Two Sum Array, Hash Table | Easy | 59 | 55.8% |
| 26 | Cherry Pickup Array, Dynamic Programming, Matrix | Hard | 56 | 37.9% |
| 27 | Valid Parentheses String, Stack | Easy | 56 | 42.3% |
| 28 | Trapping Rain Water Array, Two Pointers, Dynamic Programming, Stack, Monotonic Stack | Hard | 56 | 65.1% |
| 29 | Longest Substring Without Repeating Characters Hash Table, String, Sliding Window | Medium | 53 | 36.9% |
| 30 | Linked List Cycle Hash Table, Linked List, Two Pointers | Easy | 50 | 52.6% |
| 31 | Decode String String, Stack, Recursion | Medium | 50 | 61.2% |
| 32 | Best Time to Buy and Sell Stock Array, Dynamic Programming | Easy | 50 | 55.3% |
| 33 | Remove Boxes Array, Dynamic Programming, Memoization | Hard | 50 | 48.3% |
| 34 | Merge Sorted Array Array, Two Pointers, Sorting | Easy | 50 | 52.9% |
| 35 | Strange Printer String, Dynamic Programming | Hard | 45 | 60.8% |
| 36 | Longest Consecutive Sequence Array, Hash Table, Union Find | Medium | 45 | 47.0% |
| 37 | Letter Combinations of a Phone Number Hash Table, String, Backtracking | Medium | 45 | 63.9% |
| 38 | Move Zeroes Array, Two Pointers | Easy | 45 | 62.8% |
| 39 | 3Sum Array, Two Pointers, Sorting | Medium | 45 | 37.1% |
| 40 | Reverse Linked List Linked List, Recursion | Easy | 45 | 79.2% |
| 41 | Number of Islands Array, Depth-First Search, Breadth-First Search, Union Find, Matrix | Medium | 45 | 62.3% |
| 42 | Search a 2D Matrix Array, Binary Search, Matrix | Medium | 45 | 52.3% |
| 43 | Word Search Array, String, Backtracking, Depth-First Search, Matrix | Medium | 40 | 45.3% |
| 44 | Gas Station Array, Greedy | Medium | 40 | 46.4% |
| 45 | Remove Duplicates from Sorted Array Array, Two Pointers | Easy | 40 | 60.4% |
| 46 | Meeting Rooms II Array, Two Pointers, Greedy, Sorting, Heap (Priority Queue), Prefix Sum | Medium | 40 | 52.1% |
| 47 | Valid Palindrome Two Pointers, String | Easy | 40 | 51.0% |
| 48 | Permutation in String Hash Table, Two Pointers, String, Sliding Window | Medium | 40 | 47.2% |
| 49 | Merge k Sorted Lists Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort | Hard | 40 | 56.8% |
| 50 | Group Anagrams Array, Hash Table, String, Sorting | Medium | 40 | 70.9% |
| 51 | Single Number Array, Bit Manipulation | Easy | 40 | 76.0% |
| 52 | Find Servers That Handled Most Number of Requests Array, Greedy, Heap (Priority Queue), Ordered Set | Hard | 40 | 44.1% |
| 53 | Insert Delete GetRandom O(1) Array, Hash Table, Math, Design, Randomized | Medium | 40 | 55.0% |
| 54 | Validate IP Address String | Medium | 40 | 27.8% |
| 55 | Top K Frequent Elements Array, Hash Table, Divide and Conquer, Sorting, Heap (Priority Queue), Bucket Sort, Counting, Quickselect | Medium | 40 | 64.6% |
| 56 | Add Two Numbers Linked List, Math, Recursion | Medium | 40 | 46.2% |
| 57 | Expressive Words Array, Two Pointers, String | Medium | 40 | 46.4% |
| 58 | Edit Distance String, Dynamic Programming | Medium | 32 | 58.8% |
| 59 | Subarray Sum Equals K Array, Hash Table, Prefix Sum | Medium | 32 | 45.5% |
| 60 | Rising Temperature Database | Easy | 32 | 50.2% |
| 61 | Can Place Flowers Array, Greedy | Easy | 32 | 28.9% |
| 62 | Kth Smallest Element in a BST Tree, Depth-First Search, Binary Search Tree, Binary Tree | Medium | 32 | 75.3% |
| 63 | Missing Number Array, Hash Table, Math, Binary Search, Bit Manipulation, Sorting | Easy | 32 | 70.1% |
| 64 | Find Minimum in Rotated Sorted Array Array, Binary Search | Medium | 32 | 52.6% |
| 65 | Unique Paths Math, Dynamic Programming, Combinatorics | Medium | 32 | 65.8% |
| 66 | Zigzag Conversion String | Medium | 32 | 51.6% |
| 67 | Permutations Array, Backtracking | Medium | 32 | 80.7% |
| 68 | Sliding Window Maximum Array, Queue, Sliding Window, Heap (Priority Queue), Monotonic Queue | Hard | 32 | 47.6% |
| 69 | Compare Version Numbers Two Pointers, String | Medium | 32 | 42.3% |
| 70 | Largest Rectangle in Histogram Array, Stack, Monotonic Stack | Hard | 32 | 47.4% |
| 71 | Longest Palindromic Subsequence String, Dynamic Programming | Medium | 32 | 64.1% |
| 72 | Min Stack Stack, Design | Medium | 32 | 56.4% |
| 73 | Restore IP Addresses String, Backtracking | Medium | 32 | 53.2% |
| 74 | Reverse Words in a String Two Pointers, String | Medium | 32 | 51.9% |
| 75 | Pascal's Triangle Array, Dynamic Programming | Easy | 32 | 77.0% |
| 76 | Jump Game Array, Dynamic Programming, Greedy | Medium | 32 | 39.5% |
| 77 | Count of Integers Math, String, Dynamic Programming | Hard | 32 | 37.1% |
| 78 | Climbing Stairs Math, Dynamic Programming, Memoization | Easy | 32 | 53.5% |
| 79 | Palindromic Substrings Two Pointers, String, Dynamic Programming | Medium | 32 | 71.7% |
| 80 | Design Browser History Array, Linked List, Stack, Design, Doubly-Linked List, Data Stream | Medium | 32 | 77.7% |
| 81 | Maximum Product of Two Elements in an Array Array, Sorting, Heap (Priority Queue) | Easy | 32 | 83.2% |
| 82 | Beautiful Arrangement Array, Dynamic Programming, Backtracking, Bit Manipulation, Bitmask | Medium | 32 | 64.5% |
| 83 | Remove K Digits String, Stack, Greedy, Monotonic Stack | Medium | 32 | 34.9% |
| 84 | Product of Array Except Self Array, Prefix Sum | Medium | 32 | 67.8% |
| 85 | Number of 1 Bits Divide and Conquer, Bit Manipulation | Easy | 32 | 74.5% |
| 86 | Unique Paths II Array, Dynamic Programming, Matrix | Medium | 32 | 43.2% |
| 87 | Two Sum IV - Input is a BST Hash Table, Two Pointers, Tree, Depth-First Search, Breadth-First Search, Binary Search Tree, Binary Tree | Easy | 32 | 62.2% |
How to read this list
The tabs at the top split the questions by how recently people said they were asked in interviews. "Last 30 Days" is the past month, "Last 3 Months" is the past quarter, and so on. "All Time" is every question on record for this company.
Frequency is a score from 0 to 100 for how often a question showed up in that time window. A higher number means it came up more often, so the list starts with the most common questions first. Acceptance is the share of submissions that pass on LeetCode. Click any question to open it on LeetCode.