Qualcomm coding interview
questions, leaked.
48 problems reported across recent Qualcomm interviews. Top patterns: array, two pointers, hash table. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
Qualcomm's coding assessment leans hard on arrays. Out of 48 problems, 20 are array-based, and 46 of them are easy to medium difficulty. You're looking at bread-and-butter patterns: two-pointers, hash tables, linked lists, and math. The good news is predictability. The bad news is execution matters. You'll see Two Sum, Reverse Linked List, Merge Sorted Array, and LRU Cache in rotation. If you hit a wall mid-assessment on something unfamiliar, StealthCoder runs invisibly during the actual OA and surfaces a working solution in seconds, no proctor visibility.
Top problems at Qualcomm
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | String Compression III | MEDIUM | 100.0 | 67% | String |
| 02 | Maximum Number of Ones | HARD | 97.6 | 69% | Math · Greedy · Sorting |
| 03 | Reverse Linked List | EASY | 91.9 | 79% | Linked List · Recursion |
| 04 | Remove Nth Node From End of List | MEDIUM | 74.2 | 49% | Linked List · Two Pointers |
| 05 | Number of Islands | MEDIUM | 74.2 | 62% | Array · Depth-First Search · Breadth-First Search |
| 06 | LRU Cache | MEDIUM | 74.2 | 45% | Hash Table · Linked List · Design |
| 07 | Rotate Image | MEDIUM | 74.2 | 78% | Array · Math · Matrix |
| 08 | Middle of the Linked List | EASY | 74.2 | 81% | Linked List · Two Pointers |
| 09 | Reverse Bits | EASY | 74.2 | 63% | Divide and Conquer · Bit Manipulation |
| 10 | Merge Sorted Array | EASY | 66.9 | 53% | Array · Two Pointers · Sorting |
| 11 | Majority Element | EASY | 66.9 | 66% | Array · Hash Table · Divide and Conquer |
| 12 | Implement Queue using Stacks | EASY | 66.9 | 68% | Stack · Design · Queue |
| 13 | Two Sum | EASY | 66.9 | 56% | Array · Hash Table |
| 14 | Valid Parentheses | EASY | 66.9 | 42% | String · Stack |
| 15 | Number of 1 Bits | EASY | 66.9 | 75% | Divide and Conquer · Bit Manipulation |
| 16 | Swap Nodes in Pairs | MEDIUM | 66.9 | 67% | Linked List · Recursion |
| 17 | Palindrome Number | EASY | 66.9 | 59% | Math |
| 18 | Design Memory Allocator | MEDIUM | 66.9 | 48% | Array · Hash Table · Design |
| 19 | Climbing Stairs | EASY | 66.9 | 54% | Math · Dynamic Programming · Memoization |
| 20 | Count the Number of Fair Pairs | MEDIUM | 56.6 | 53% | Array · Two Pointers · Binary Search |
| 21 | Trapping Rain Water | HARD | 56.6 | 65% | Array · Two Pointers · Dynamic Programming |
| 22 | Course Schedule II | MEDIUM | 56.6 | 53% | Depth-First Search · Breadth-First Search · Graph |
| 23 | Design Circular Queue | MEDIUM | 56.6 | 53% | Array · Linked List · Design |
| 24 | Power of Two | EASY | 56.6 | 48% | Math · Bit Manipulation · Recursion |
| 25 | Merge Intervals | MEDIUM | 56.6 | 49% | Array · Sorting |
| 26 | Serialize and Deserialize Binary Tree | HARD | 56.6 | 59% | String · Tree · Depth-First Search |
| 27 | Longest Substring Without Repeating Characters | MEDIUM | 56.6 | 37% | Hash Table · String · Sliding Window |
| 28 | Best Time to Buy and Sell Stock II | MEDIUM | 56.6 | 70% | Array · Dynamic Programming · Greedy |
| 29 | Length of Last Word | EASY | 56.6 | 56% | String |
| 30 | Remove Duplicates from Sorted Array | EASY | 56.6 | 60% | Array · Two Pointers |
| 31 | Is Subsequence | EASY | 56.6 | 48% | Two Pointers · String · Dynamic Programming |
| 32 | Reverse Nodes in k-Group | HARD | 56.6 | 63% | Linked List · Recursion |
| 33 | Two Sum II - Input Array Is Sorted | MEDIUM | 56.6 | 63% | Array · Two Pointers · Binary Search |
| 34 | Maximum Subarray | MEDIUM | 56.6 | 52% | Array · Divide and Conquer · Dynamic Programming |
| 35 | Find Winner on a Tic Tac Toe Game | EASY | 56.6 | 54% | Array · Hash Table · Matrix |
| 36 | Trapping Rain Water II | HARD | 56.6 | 59% | Array · Breadth-First Search · Heap (Priority Queue) |
| 37 | Permutations | MEDIUM | 56.6 | 81% | Array · Backtracking |
| 38 | Power of Four | EASY | 56.6 | 49% | Math · Bit Manipulation · Recursion |
| 39 | First Unique Character in a String | EASY | 56.6 | 64% | Hash Table · String · Queue |
| 40 | Single Number | EASY | 56.6 | 76% | Array · Bit Manipulation |
| 41 | Linked List Cycle | EASY | 56.6 | 53% | Hash Table · Linked List · Two Pointers |
| 42 | Kth Largest Element in an Array | MEDIUM | 56.6 | 68% | Array · Divide and Conquer · Sorting |
| 43 | Rectangle Overlap | EASY | 56.6 | 46% | Math · Geometry |
| 44 | String to Integer (atoi) | MEDIUM | 56.6 | 19% | String |
| 45 | Reverse Integer | MEDIUM | 56.6 | 30% | Math |
| 46 | Maximum Depth of Binary Tree | EASY | 56.6 | 77% | Tree · Depth-First Search · Breadth-First Search |
| 47 | Pow(x, n) | MEDIUM | 56.6 | 37% | Math · Recursion |
| 48 | Design Tic-Tac-Toe | MEDIUM | 56.6 | 59% | Array · Hash Table · Design |
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 Qualcomm 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- array20 · 42%
- two pointers9 · 19%
- hash table9 · 19%
- math9 · 19%
- linked list8 · 17%
- string8 · 17%
- recursion6 · 13%
- sorting6 · 13%
- design6 · 13%
- divide and conquer5 · 10%
Arrays dominate Qualcomm's question pool, which means you drill in-place operations, sliding windows, and traversal patterns first. Two-pointers and hash tables split the remaining load roughly equally. The difficulty curve is forgiving: 46 percent easy, 44 percent medium, only 10 percent hard. You're not walking into a gauntlet. What matters is speed and correctness on the fundamentals. String Compression, Rotate Image, Number of Islands, and LRU Cache are the medium-tier gatekeepers; master those and you're solid. Recursion, sorting, and design pop up in targeted spots. Since arrays and two-pointers lock up nearly half the problems, that's where your first week goes. StealthCoder becomes your safety net if a greedy twist or a heap variant shows up and you blank.
Companies with similar patterns
If you prepped for Qualcomm, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass Qualcomm.
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.
Qualcomm interview FAQ
How many array problems should I solve before the Qualcomm assessment?+
You need to own the fundamentals on all 20 array problems in the Qualcomm report. Focus on in-place operations, merging, rotation, and island-style traversals. Since arrays account for 42 percent of their pool, array fluency is non-negotiable. Aim for zero hesitation on Merge Sorted Array, Rotate Image, and Number of Islands.
Is two-pointers enough to prep for, or should I study hash tables first?+
Both appear equally in Qualcomm's data: 9 problems each. Two-pointers is slightly faster to master and shows up in linked-list contexts (Middle of the Linked List, Remove Nth Node). Start with two-pointers because it builds confidence fast, then move to hash tables. You'll overlap on problems like Two Sum anyway.
What's the hardest topic I should prepare for at Qualcomm?+
Only 5 of 48 problems are hard, and they're spread across design, dynamic-programming, and divide-and-conquer. LRU Cache is the most common hard problem. If you're short on time, skip the hard tier initially. Master the 46 easy and medium problems first; that's 96 percent of what they ask.
Should I prepare linked-list problems separately, or are they baked into two-pointers?+
Qualcomm has 8 linked-list problems, and most involve two-pointers or recursion. Reverse Linked List, Middle of the Linked List, and Remove Nth Node are the core patterns. Study them as a cluster because the techniques overlap heavily with array two-pointers.
How much time should I spend on string and math problems?+
String and math each have 8 and 9 problems respectively, but they're lower-frequency patterns at Qualcomm compared to arrays. If you have two weeks, drill them in week two after arrays and linked lists are solid. String Compression III and Maximum Number of Ones are the outliers; treat them as bonus coverage.