LeetCode 155 Min Stack - Problem Statement

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

MinStack(): Initialize the stack.

push(val): Push val onto the stack.

pop(): Remove the top element.

top(): Get the top element.

getMin(): Retrieve the minimum element.

All operations must work in $O(1)$ time.

Constraints: $-2^{31} \le val \le 2^{31} - 1$. Up to $3 \times 10^4$ operations.