Mid Stacks / Design DSA & Coding Interviews

Explain Min Stack design.

Q: Explain Min Stack design.

Short answer: Keep a normal stack plus an auxiliary stack of current minima (or store pairs). push/pop/top/getMin all O(1). On push, push min(x, currentMin) onto the min stack. Complexity All operations O(1), Space O(n). Do not scan the stack for getMin — that is O(n) and fails the prompt.

Short answer: Keep a normal stack plus an auxiliary stack of current minima (or store pairs). push/pop/top/getMin all O(1). On push, push min(x, currentMin) onto the min stack.

Complexity

All operations O(1), Space O(n).

Do not scan the stack for getMin — that is O(n) and fails the prompt.

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