Amazon coding interview
questions, leaked.
199 problems reported across recent Amazon interviews. Top patterns: array, string, hash table. The list below is what most candidates actually saw, plus the honest play if you can't grind all of it.
Amazon's interview loop hits you with 199 problems across their online assessment, and 122 of them are medium or hard. You're looking at a heavy diet of arrays (100 problems), strings (53), and hash tables (41). The difficulty curve is brutal: 61% medium, 17% hard. You could grind for months and still miss the exact pattern they ask. That's where StealthCoder comes in. If you blank on a hash-table or DP problem mid-assessment, it solves it in seconds, invisible to the proctor. But first, you need to know what actually matters.
Top problems at Amazon
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Two Sum | EASY | 100.0 | 56% | Array · Hash Table |
| 02 | Best Time to Buy and Sell Stock | EASY | 0.0 | 55% | Array · Dynamic Programming |
| 03 | LRU Cache | MEDIUM | 0.0 | 45% | Hash Table · Linked List · Design |
| 04 | Number of Islands | MEDIUM | 0.0 | 62% | Array · Depth-First Search · Breadth-First Search |
| 05 | Reorganize String | MEDIUM | 0.0 | 56% | Hash Table · String · Greedy |
| 06 | Maximum Frequency After Subarray Operation | MEDIUM | 0.0 | 27% | Array · Hash Table · Dynamic Programming |
| 07 | Trapping Rain Water | HARD | 85.9 | 65% | Array · Two Pointers · Dynamic Programming |
| 08 | Longest Substring Without Repeating Characters | MEDIUM | 82.6 | 37% | Hash Table · String · Sliding Window |
| 09 | Merge Sorted Array | EASY | 81.4 | 53% | Array · Two Pointers · Sorting |
| 10 | Koko Eating Bananas | MEDIUM | 0.0 | 49% | Array · Binary Search |
| 11 | Group Anagrams | MEDIUM | 78.9 | 71% | Array · Hash Table · String |
| 12 | Add Two Numbers | MEDIUM | 77.9 | 46% | Linked List · Math · Recursion |
| 13 | Valid Parentheses | EASY | 77.7 | 42% | String · Stack |
| 14 | Longest Palindromic Substring | MEDIUM | 77.1 | 36% | Two Pointers · String · Dynamic Programming |
| 15 | 3Sum | MEDIUM | 76.7 | 37% | Array · Two Pointers · Sorting |
| 16 | Top K Frequent Elements | MEDIUM | 0.0 | 65% | Array · Hash Table · Divide and Conquer |
| 17 | Merge Intervals | MEDIUM | 75.8 | 49% | Array · Sorting |
| 18 | Median of Two Sorted Arrays | HARD | 75.3 | 44% | Array · Binary Search · Divide and Conquer |
| 19 | Container With Most Water | MEDIUM | 75.1 | 58% | Array · Two Pointers · Greedy |
| 20 | Lowest Common Ancestor of a Binary Tree | MEDIUM | 0.0 | 67% | Tree · Depth-First Search · Binary Tree |
| 21 | Longest Repeating Character Replacement | MEDIUM | 0.0 | 57% | Hash Table · String · Sliding Window |
| 22 | Merge k Sorted Lists | HARD | 71.4 | 57% | Linked List · Divide and Conquer · Heap (Priority Queue) |
| 23 | Maximum Subarray | MEDIUM | 71.1 | 52% | Array · Divide and Conquer · Dynamic Programming |
| 24 | Longest Common Prefix | EASY | 70.8 | 45% | String · Trie |
| 25 | Jump Game | MEDIUM | 69.8 | 39% | Array · Dynamic Programming · Greedy |
| 26 | Climbing Stairs | EASY | 69.8 | 54% | Math · Dynamic Programming · Memoization |
| 27 | Candy | HARD | 0.0 | 47% | Array · Greedy |
| 28 | Meeting Rooms II | MEDIUM | 0.0 | 52% | Array · Two Pointers · Greedy |
| 29 | House Robber | MEDIUM | 0.0 | 52% | Array · Dynamic Programming |
| 30 | Generate Parentheses | MEDIUM | 68.6 | 77% | String · Dynamic Programming · Backtracking |
| 31 | Letter Combinations of a Phone Number | MEDIUM | 68.2 | 64% | Hash Table · String · Backtracking |
| 32 | Spiral Matrix | MEDIUM | 67.2 | 54% | Array · Matrix · Simulation |
| 33 | Search in Rotated Sorted Array | MEDIUM | 67.1 | 43% | Array · Binary Search |
| 34 | Palindrome Number | EASY | 66.9 | 59% | Math |
| 35 | Roman to Integer | EASY | 66.1 | 65% | Hash Table · Math · String |
| 36 | Merge Two Sorted Lists | EASY | 66.0 | 67% | Linked List · Recursion |
| 37 | Reverse Integer | MEDIUM | 65.3 | 30% | Math |
| 38 | Min Stack | MEDIUM | 0.0 | 56% | Stack · Design |
| 39 | Best Time to Buy and Sell Stock II | MEDIUM | 0.0 | 70% | Array · Dynamic Programming · Greedy |
| 40 | Concatenated Words | HARD | 0.0 | 49% | Array · String · Dynamic Programming |
| 41 | Coin Change | MEDIUM | 0.0 | 46% | Array · Dynamic Programming · Breadth-First Search |
| 42 | LFU Cache | HARD | 0.0 | 47% | Hash Table · Linked List · Design |
| 43 | Rotting Oranges | MEDIUM | 0.0 | 57% | Array · Breadth-First Search · Matrix |
| 44 | Insert Delete GetRandom O(1) | MEDIUM | 0.0 | 55% | Array · Hash Table · Math |
| 45 | Flood Fill | EASY | 0.0 | 66% | Array · Depth-First Search · Breadth-First Search |
| 46 | Fizz Buzz | EASY | 0.0 | 74% | Math · String · Simulation |
| 47 | Rotate Image | MEDIUM | 63.9 | 78% | Array · Math · Matrix |
| 48 | Word Search | MEDIUM | 63.6 | 45% | Array · String · Backtracking |
| 49 | Next Permutation | MEDIUM | 63.2 | 43% | Array · Two Pointers |
| 50 | Remove Duplicates from Sorted Array | EASY | 62.9 | 60% | Array · Two Pointers |
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 Amazon OA. The proctor cannot see it. Screen share cannot detect it. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround.
Get StealthCoder- array100 · 50%
- string53 · 27%
- hash table41 · 21%
- dynamic programming35 · 18%
- math31 · 16%
- two pointers28 · 14%
- depth first search24 · 12%
- sorting24 · 12%
- breadth first search20 · 10%
- backtracking20 · 10%
Arrays dominate Amazon's bar by a landslide. Two Sum, Best Time to Buy and Sell Stock, and Merge Sorted Array are the bread and butter. Strings and hash tables sit a close second and third, often overlapping: Group Anagrams, Longest Substring Without Repeating Characters. Dynamic programming shows up in 35 problems, but it's woven into array and string questions, not always labeled as such. Two-pointer technique runs through Trapping Rain Water, 3Sum, and Longest Palindromic Substring. If you've got a week, master arrays and hash tables first, then string manipulations. Tree and graph problems (DFS, BFS) matter less than you'd think at 20-24 problems each. StealthCoder becomes your hedge on the DP questions that don't look like DP at first glance, the ones where the pattern doesn't click until you're live.
Companies with similar patterns
If you prepped for Amazon, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Amazon.
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. Built because the OA filter rejects engineers who'd pass the on-site. That's a broken filter. This is the workaround. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Amazon interview FAQ
Should I study dynamic programming before arrays for Amazon?+
No. Arrays appear in 100 of 199 problems. Master Two Sum, Best Time to Buy and Sell Stock, and Merge Sorted Array first. DP shows up frequently but often embedded in array problems. Once array fundamentals lock in, DP patterns will feel less foreign.
How many hash-table problems should I solve before the OA?+
At least 15 to 20. Hash tables hit 41 problems on Amazon's list and overlap heavily with string questions like Group Anagrams and Longest Substring Without Repeating Characters. They're the connector between arrays and string problems.
Is two-pointers enough to crack Trapping Rain Water and 3Sum?+
It's the core technique, but not sufficient alone. Trapping Rain Water also needs dynamic programming or stack thinking. 3Sum requires sorting and pointer movement together. Practice both problems specifically, not just the technique in isolation.
What should I prioritize if I have three days left?+
Arrays and strings, no debate. Together they represent 153 of 199 problems. Focus on Two Sum, Best Time to Buy and Sell Stock, Group Anagrams, and Longest Substring Without Repeating Characters. These patterns repeat across difficulty levels.
Do I need to master trees and graphs for Amazon's assessment?+
Lower priority than arrays and strings. DFS and BFS combined appear in roughly 44 problems. If you have time after arrays, strings, and hash tables lock in, then study Number of Islands and basic tree traversal. Not required for a solid score.