All companies
Citadel
6 Easy54 Medium29 Hard89 total
| No. | Problem | Difficulty | Frequency |
|---|---|---|---|
| 239 | Sliding Window Maximum | Hard | |
| 647 | Palindromic Substrings | Medium | |
| 2484 | Count Palindromic Subsequences | Hard | |
| 121 | Best Time to Buy and Sell Stock | Easy | |
| 146 | LRU Cache | Medium | |
| 295 | Find Median from Data Stream | Hard | |
| 3186 | Maximum Total Damage With Spell Casting | Medium | |
| 2361 | Minimum Costs Using the Train Line | Hard | |
| 1515 | Best Position for a Service Centre | Hard | |
| 2661 | First Completely Painted Row or Column | Medium | |
| 2702 | Minimum Operations to Make Numbers Non-positive | Hard | |
| 718 | Maximum Length of Repeated Subarray | Medium | |
| 56 | Merge Intervals | Medium | |
| 1801 | Number of Orders in the Backlog | Medium | |
| 287 | Find the Duplicate Number | Medium | |
| 380 | Insert Delete GetRandom O(1) | Medium | |
| 399 | Evaluate Division | Medium | |
| 460 | LFU Cache | Hard | |
| 2958 | Length of Longest Subarray With at Most K Frequency | Medium | |
| 2050 | Parallel Courses III | Hard | |
| 759 | Employee Free Time | Hard | |
| 1229 | Meeting Scheduler | Medium | |
| 23 | Merge k Sorted Lists | Hard | |
| 37 | Sudoku Solver | Hard | |
| 124 | Binary Tree Maximum Path Sum | Hard | |
| 150 | Evaluate Reverse Polish Notation | Medium | |
| 200 | Number of Islands | Medium | |
| 297 | Serialize and Deserialize Binary Tree | Hard | |
| 49 | Group Anagrams | Medium | |
| 622 | Design Circular Queue | Medium | |
| 412 | Fizz Buzz | Easy | |
| 765 | Couples Holding Hands | Hard | |
| 210 | Course Schedule II | Medium | |
| 69 | Sqrt(x) | Easy | |
| 1606 | Find Servers That Handled Most Number of Requests | Hard | |
| 332 | Reconstruct Itinerary | Hard | |
| 1004 | Max Consecutive Ones III | Medium | |
| 2598 | Smallest Missing Non-negative Integer After Operations | Medium | |
| 127 | Word Ladder | Hard | |
| 348 | Design Tic-Tac-Toe | Medium | |
| 981 | Time Based Key-Value Store | Medium | |
| 39 | Combination Sum | Medium | |
| 46 | Permutations | Medium | |
| 1048 | Longest String Chain | Medium | |
| 123 | Best Time to Buy and Sell Stock III | Hard | |
| 207 | Course Schedule | Medium | |
| 221 | Maximal Square | Medium | |
| 279 | Perfect Squares | Medium | |
| 1268 | Search Suggestions System | Medium | |
| 79 | Word Search | Medium | |
| 208 | Implement Trie (Prefix Tree) | Medium | |
| 631 | Design Excel Sum Formula | Hard | |
| 1670 | Design Front Middle Back Queue | Medium | |
| 767 | Reorganize String | Medium | |
| 1203 | Sort Items by Groups Respecting Dependencies | Hard | |
| 346 | Moving Average from Data Stream | Easy | |
| 2044 | Count Number of Maximum Bitwise-OR Subsets | Medium | |
| 126 | Word Ladder II | Hard | |
| 17 | Letter Combinations of a Phone Number | Medium | |
| 70 | Climbing Stairs | Easy | |
| 256 | Paint House | Medium | |
| 1632 | Rank Transform of a Matrix | Hard | |
| 103 | Binary Tree Zigzag Level Order Traversal | Medium | |
| 50 | Pow(x, n) | Medium | |
| 875 | Koko Eating Bananas | Medium | |
| 149 | Max Points on a Line | Hard | |
| 5 | Longest Palindromic Substring | Medium | |
| 204 | Count Primes | Medium | |
| 253 | Meeting Rooms II | Medium | |
| 34 | Find First and Last Position of Element in Sorted Array | Medium | |
| 31 | Next Permutation | Medium | |
| 98 | Validate Binary Search Tree | Medium | |
| 151 | Reverse Words in a String | Medium | |
| 1155 | Number of Dice Rolls With Target Sum | Medium | |
| 465 | Optimal Account Balancing | Hard | |
| 188 | Best Time to Buy and Sell Stock IV | Hard | |
| 155 | Min Stack | Medium | |
| 53 | Maximum Subarray | Medium | |
| 1 | Two Sum | Easy | |
| 782 | Transform to Chessboard | Hard | |
| 1244 | Design A Leaderboard | Medium | |
| 3484 | Design Spreadsheet | Medium | |
| 588 | Design In-Memory File System | Hard | |
| 714 | Best Time to Buy and Sell Stock with Transaction Fee | Medium | |
| 688 | Knight Probability in Chessboard | Medium | |
| 8 | String to Integer (atoi) | Medium | |
| 1411 | Number of Ways to Paint N × 3 Grid | Hard | |
| 42 | Trapping Rain Water | Hard | |
| 802 | Find Eventual Safe States | Medium |