Min Stack
Design a stack that supports push, pop, top, and getMin in O(1) time. Think about: How can you track the minimum efficiently? Hint: Consider using an auxiliary structure to track minimums. Example: push(-2), push(0), push(-3) get_min() → -3 pop() top() → 0 get_min() → -2
Min Stack is all about maintaining a clear stack meaning as you process input. Interviewers love it because it reveals your stack invariants and your edge-case discipline. The classic mistake is not being clear about what your stack represents at each step.
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