Coding & Algorithms (DSA)
Monotonic Stack & Deque
6 practice questions. Free questions open a full answer guide; the rest unlock with Pro.
- Explain how a monotonic stack solves the 'next greater element' problem in linear time, and how you recognize at review time that a quadratic nested-loop solution should actually be a monotonic stack.
- When the next-greater-element pattern is generalized to a sliding-window maximum, why do you switch from a monotonic stack to a monotonic deque, and what does the deque let you do that the stack can't?Go Pro
- Why is a deque the right structure for the 'sliding window maximum' problem, and what invariant do you maintain in it?Go Pro
- For a sliding-window-maximum over a stream, why is a monotonic deque the right tool instead of a heap, and what exactly does the deque hold at any moment?Go Pro
- What is a monotonic stack, and what kind of problem signals that you should reach for one?Go Pro
- What is a monotonic stack, and how does it solve next-greater-element problems in linear time despite the inner loop that pops multiple items?Go Pro
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