Monotonic Stack interview questions
39 monotonic stack problems tagged across recent interview reports. Drilled most heavily by amazon, microsoft, and google.
Monotonic Stack is a pattern that shows up in 39 problems across major tech interviews. It's the answer when you need to find the next greater/smaller element, track ranges, or compute spans efficiently. Amazon, Microsoft, and Google all weight it heavily, roughly 15 to 16 problems each. The pattern works because it processes elements in a single pass while maintaining a useful order, cutting what could be O(n²) brute force down to O(n). If a hard variant lands in your live OA, StealthCoder solves it in seconds, invisible to the proctor.
Most-asked monotonic stack problems
You can't drill every monotonic stack variant before the assessment. StealthCoder runs invisibly during screen share and solves whichever variant they throw at you. No browser extension. No detection signature. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop.
Get StealthCoderMonotonic Stack keeps a stack of candidates in increasing or decreasing order. When you see a new element, you pop elements that violate the order and record what you learned before discarding them. The core move: peek at what's leaving the stack (your answer for that element), then decide whether the current element joins the stack. You'll recognize it by the prompt asking for 'next greater element', 'previous smaller', spans, or rectangle problems like Largest Rectangle in Histogram. Amazon and Microsoft drill this relentlessly because it appears in pricing, building visibility, and time-series problems. Bloomberg, DE Shaw, and Goldman Sachs hit it too. The stack itself is usually an index stack, not values. Start with Daily Temperatures and Car Fleet, then move to harder geometry like Largest Rectangle in Histogram. If you freeze on a monotonic variant during your assessment, StealthCoder is your hedge, it recognizes the pattern instantly and outputs the solution while you stay invisible.
Companies that hire most on monotonic stack
39 monotonic stack problems.
You won't drill them all. Pass anyway.
Monotonic Stack is one of the patterns interviews actually filter on. Memorizing every variant in a week is a fantasy. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds, no matter which monotonic stack flavor lands in your live OA. Built by an Amazon engineer who used it to pass JPMorgan's OA and system design loop. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Monotonic Stack interview FAQ
How do I know when to use Monotonic Stack?+
Look for problems asking 'next/previous greater/smaller element', span or range queries, or histograms. Prompts often say 'for each element, find...' paired with a direction. Problems like Daily Temperatures and Buildings with an Ocean View are textbook signals. If you could brute-force it with nested loops in O(n²), monotonic stack likely drops it to O(n).
Do I need to master all Monotonic Stack variants?+
You need the core: next greater, next smaller, and how to adapt it to 2D (like Largest Rectangle in Histogram). Complex variants like Find Building Where Alice and Bob Can Meet are rarer. Focus on the 5-6 fundamentals first, then expand. Amazon and Microsoft test the core heavily.
Is Monotonic Stack the hardest pattern for these companies?+
No. It's high-frequency and medium difficulty. Amazon has 16 problems, but that includes easy to hard. Companies like Amazon and Microsoft pair it with dynamic programming or graphs. It's a 'you should know this' pattern, not necessarily the final gatekeeper.
Should I store indices or values in the stack?+
Almost always indices. You need to compute distances, ranges, or look up original values. Storing indices lets you reference the array and record answers. Only store values if the problem explicitly asks for them.
Which company drills Monotonic Stack the hardest?+
Amazon and Microsoft tie at 16 problems each. Google is close at 15. Bloomberg, Flipkart, DE Shaw, PhonePe, and Zoho each have 12 to 13. If you're interviewing at any of these, stack problems are mandatory prep.