PubMatic coding interview
questions, leaked.
3 problems reported across recent PubMatic interviews. Top patterns: array, two pointers, string. The list below is what most reported candidates actually saw, plus the honest play if you can't grind all of it.
PubMatic's coding assessment hits you with a tight mix of array, two-pointer, and string problems. You're looking at one easy, one medium, one hard. The good news: the pool is small, and the patterns repeat. Array work dominates, especially two-pointer traversals and stack-based logic. If you hit a wall on "Trapping Rain Water" or "Meeting Rooms II" mid-assessment, StealthCoder runs invisible behind the proctor's view and surfaces a working solution in seconds. That's your hedge for the curveballs you didn't see coming.
Top problems at PubMatic
| # | Problem | Diff | Frequency | Pass % | Patterns |
|---|---|---|---|---|---|
| 01 | Longest Common Prefix | EASY | 100.0 | 45% | String · Trie |
| 02 | Trapping Rain Water | HARD | 89.5 | 65% | Array · Two Pointers · Dynamic Programming |
| 03 | Meeting Rooms II | MEDIUM | 89.5 | 52% | Array · Two Pointers · Greedy |
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 PubMatic OA. The proctor cannot see it. Screen share cannot detect it. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoder- array2 · 67%
- two pointers2 · 67%
- string1 · 33%
- trie1 · 33%
- dynamic programming1 · 33%
- stack1 · 33%
- monotonic stack1 · 33%
- greedy1 · 33%
- sorting1 · 33%
- heap priority queue1 · 33%
Two patterns own this assessment: array manipulation (appearing in every single problem) and two-pointer technique (present in two of three). "Trapping Rain Water" is the spike. It demands stack, monotonic stack, dynamic programming, and two-pointers all at once. It's a compression of multiple concepts. "Meeting Rooms II" layers greedy logic with heap operations. "Longest Common Prefix" is your warm-up, a trie-or-brute-force string problem. The difficulty spread (easy, medium, hard) means you'll face a real jump in complexity. Drill two-pointer patterns and monotonic stacks first. Stack-based problems are where candidates blank. If you freeze on the hard problem, StealthCoder is the real-time solution. Don't walk in unprepared for stack logic.
Companies with similar patterns
If you prepped for PubMatic, these companies recycle ~60% of the same topics.
You've seen the list.
Now make sure you pass PubMatic.
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 by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
PubMatic interview FAQ
Should I prioritize two-pointers or arrays first for PubMatic?+
Both appear together in two of three problems, so practice them as a unit. Start with array problems that use two-pointer technique: "Meeting Rooms II" and "Trapping Rain Water" are your core. Don't skip monotonic stack patterns. They're less familiar than two-pointers but critical for the hard problem.
Is the easy problem enough to warm up with?+
"Longest Common Prefix" is genuinely easy, but don't oversleep on it. It's a string/trie problem, the only one in the set. Do it in under 10 minutes, then move to the medium and hard. The hard problem is where the difficulty cliff lives.
How much time should I spend on 'Trapping Rain Water'?+
It's a Hard that pulls from five different topics. Don't expect a fast solve. Spend 20 to 30 minutes mapping the monotonic stack approach. If you hit the wall, move on and return if time allows. It's exactly the kind of problem where StealthCoder catches you if you blank.
What's the difference between their array problems?+
"Meeting Rooms II" uses arrays with greedy and heap logic. "Trapping Rain Water" uses arrays with stack and two-pointers. Both require seeing the array as a data structure with spatial relationships, not just a list. Practice both patterns separately.
Is dynamic programming needed for this assessment?+
Yes, but only for "Trapping Rain Water", where it's one of several valid approaches. Don't spend days on DP. Focus on the monotonic stack solution first, it's faster and more elegant for this specific problem.