Cisco coding interview
questions, leaked.
87 problems reported across recent Cisco interviews. Top patterns: array, string, dynamic programming. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Cisco's interview hits you with 87 problems across 6 rounds, and 57 percent are medium or hard. Arrays dominate (50 problems), but strings, dynamic programming, and hash tables form a nasty trio that candidates underestimate. You're looking at design questions (LRU Cache, Implement Router) mixed with string pattern work (Longest Palindromic Substring, Word Search II). If you blank on a hash-table or DP problem mid-assessment, StealthCoder runs invisibly and surfaces a working solution in seconds. Most candidates chase leetcode volume. You need precision on the patterns that actually appear.
Top problems at Cisco
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Longest Palindromic Substring | MEDIUM | 100.0 | 36% | Two Pointers · String · Dynamic Programming |
| 02 | House Robber | MEDIUM | 98.1 | 52% | Array · Dynamic Programming |
| 03 | Predict the Winner | MEDIUM | 98.1 | 56% | Array · Math · Dynamic Programming |
| 04 | Lucky Numbers in a Matrix | EASY | 84.8 | 80% | Array · Matrix |
| 05 | Rotate Image | MEDIUM | 84.8 | 78% | Array · Math · Matrix |
| 06 | Spiral Matrix | MEDIUM | 84.1 | 54% | Array · Matrix · Simulation |
| 07 | Fizz Buzz | EASY | 69.8 | 74% | Math · String · Simulation |
| 08 | LRU Cache | MEDIUM | 66.8 | 45% | Hash Table · Linked List · Design |
| 09 | Snakes and Ladders | MEDIUM | 66.8 | 48% | Array · Breadth-First Search · Matrix |
| 10 | Number of Valid Words in a Sentence | EASY | 66.8 | 30% | String |
| 11 | Maximum Difference Between Increasing Elements | EASY | 65.1 | 66% | Array |
| 12 | Merge Intervals | MEDIUM | 65.1 | 49% | Array · Sorting |
| 13 | Find Third Transaction | MEDIUM | 65.1 | 54% | Database |
| 14 | Implement Router | MEDIUM | 63.2 | 22% | Array · Hash Table · Binary Search |
| 15 | Word Search II | HARD | 63.2 | 37% | Array · String · Backtracking |
| 16 | Maximum Subarray | MEDIUM | 63.2 | 52% | Array · Divide and Conquer · Dynamic Programming |
| 17 | Find the Largest Area of Square Inside Two Rectangles | MEDIUM | 63.2 | 45% | Array · Math · Geometry |
| 18 | Check if Binary String Has at Most One Segment of Ones | EASY | 63.2 | 39% | String |
| 19 | Sum of k-Mirror Numbers | HARD | 63.2 | 42% | Math · Enumeration |
| 20 | Minimum Cost to Make Array Equal | HARD | 63.2 | 46% | Array · Binary Search · Greedy |
| 21 | Number of Equal Count Substrings | MEDIUM | 63.2 | 45% | Hash Table · String · Sliding Window |
| 22 | Max Points on a Line | HARD | 58.9 | 29% | Array · Hash Table · Math |
| 23 | Stone Game | MEDIUM | 58.9 | 72% | Array · Math · Dynamic Programming |
| 24 | Happy Number | EASY | 58.9 | 58% | Hash Table · Math · Two Pointers |
| 25 | Two Sum | EASY | 58.9 | 56% | Array · Hash Table |
| 26 | Cherry Pickup | HARD | 56.3 | 38% | Array · Dynamic Programming · Matrix |
| 27 | Valid Parentheses | EASY | 56.3 | 42% | String · Stack |
| 28 | Trapping Rain Water | HARD | 56.3 | 65% | Array · Two Pointers · Dynamic Programming |
| 29 | Longest Substring Without Repeating Characters | MEDIUM | 53.2 | 37% | Hash Table · String · Sliding Window |
| 30 | Linked List Cycle | EASY | 49.7 | 53% | Hash Table · Linked List · Two Pointers |
| 31 | Merge Sorted Array | EASY | 49.7 | 53% | Array · Two Pointers · Sorting |
| 32 | Remove Boxes | HARD | 49.7 | 48% | Array · Dynamic Programming · Memoization |
| 33 | Decode String | MEDIUM | 49.7 | 61% | String · Stack · Recursion |
| 34 | Best Time to Buy and Sell Stock | EASY | 49.7 | 55% | Array · Dynamic Programming |
| 35 | Letter Combinations of a Phone Number | MEDIUM | 45.3 | 64% | Hash Table · String · Backtracking |
| 36 | Number of Islands | MEDIUM | 45.3 | 62% | Array · Depth-First Search · Breadth-First Search |
| 37 | Move Zeroes | EASY | 45.3 | 63% | Array · Two Pointers |
| 38 | Reverse Linked List | EASY | 45.3 | 79% | Linked List · Recursion |
| 39 | Search a 2D Matrix | MEDIUM | 45.3 | 52% | Array · Binary Search · Matrix |
| 40 | Strange Printer | HARD | 45.3 | 61% | String · Dynamic Programming |
| 41 | 3Sum | MEDIUM | 45.3 | 37% | Array · Two Pointers · Sorting |
| 42 | Longest Consecutive Sequence | MEDIUM | 45.3 | 47% | Array · Hash Table · Union Find |
| 43 | Remove Duplicates from Sorted Array | EASY | 39.8 | 60% | Array · Two Pointers |
| 44 | Meeting Rooms II | MEDIUM | 39.8 | 52% | Array · Two Pointers · Greedy |
| 45 | Permutation in String | MEDIUM | 39.8 | 47% | Hash Table · Two Pointers · String |
| 46 | Word Search | MEDIUM | 39.8 | 45% | Array · String · Backtracking |
| 47 | Add Two Numbers | MEDIUM | 39.8 | 46% | Linked List · Math · Recursion |
| 48 | Gas Station | MEDIUM | 39.8 | 46% | Array · Greedy |
| 49 | Expressive Words | MEDIUM | 39.8 | 46% | Array · Two Pointers · String |
| 50 | Single Number | EASY | 39.8 | 76% | Array · Bit Manipulation |
Frequencies derived from public community-tagged interview reports. Click a row to view on LeetCode.
You have a week, maybe less. You can't out-grind the list above. StealthCoder runs invisibly during the actual Cisco OA. The proctor cannot see it. Screen share cannot detect it. Made for the engineer who has done the work but might still blank with a webcam pointed at him.
Get StealthCoder- array50 · 57%
- string26 · 30%
- dynamic programming20 · 23%
- hash table17 · 20%
- two pointers16 · 18%
- math14 · 16%
- matrix10 · 11%
- sorting9 · 10%
- greedy7 · 8%
- stack7 · 8%
Array and string problems make up 87 percent of Cisco's question pool, but the real trap is dynamic programming hiding inside them (House Robber, Predict the Winner). Medium difficulty dominates (57 percent), so expect multi-step thinking, not easy wins. Two-pointers and matrix rotation show up repeatedly, which means you need fluid movement through 2D space. Design problems like LRU Cache and Implement Router test whether you understand hash tables and linked lists under pressure. Drill arrays and strings first, because they're your volume. Then anchor DP patterns to concrete problems (House Robber, Longest Palindromic Substring). StealthCoder is your hedge for the live OA when you hit a DP twist you didn't anticipate.
Companies with similar patterns
If you prepped for Cisco, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Cisco.
Memorizing every problem above in a week is a fantasy. StealthCoder is the hedge: an AI overlay that's invisible during screen share. It reads the problem on screen and surfaces a working solution in under 2 seconds. Made for the engineer who has done the work but might still blank with a webcam pointed at him. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Cisco interview FAQ
How many array and string problems should I solve before the Cisco OA?+
Cisco's top 12 topics are array-heavy (50 problems) plus strings (26 problems). Solve the toppers: Rotate Image, Spiral Matrix, Merge Intervals, and Number of Valid Words in a Sentence. Then hit dynamic programming variants (House Robber, Longest Palindromic Substring). That's your base. You have maybe 20-30 problems to drill before the test.
Is dynamic programming enough to prep for Cisco's medium problems?+
No. DP appears in 20 problems, but it's wrapped in arrays, strings, and game theory. Predict the Winner mixes DP with recursion and game logic. House Robber is pure DP but array-dependent. Study DP patterns in isolation first, then solve them within array and string contexts. Don't treat DP as standalone.
What should I drill first for Cisco: two-pointers or hash tables?+
Arrays first (50 problems total), then hash tables (17 problems). Two-pointers show up in Longest Palindromic Substring and Merge Intervals, so they're a sub-skill of array mastery. Hash tables hit harder in design (LRU Cache, Implement Router). Arrays unlock 60 percent of the test. Start there, add hash tables by day three.
Are Cisco's easy problems worth my time?+
Yes, but briefly. 24 of 87 are easy (Fizz Buzz, Lucky Numbers, Maximum Difference). Solve them in under an hour to confirm you can read and implement. Then move to medium. Easy problems won't cost you the interview, but they're not where the time wins happen.
What's the hardest topic to study for Cisco's OA?+
Word Search II (hard, backtracking plus trie) and design questions (LRU Cache, Implement Router) trip up candidates most. Word Search II needs trie knowledge most don't have. LRU Cache requires doubly-linked list fluency under time pressure. Drill these two in the final 48 hours. If you blank on either, you'll need a real-time solution.