min_stack.py

# Problem url: https://leetcode.com/problems/min-stack, Medium


class MinStack:

    def __init__(self):
        self.st = []

    def push(self, val: int) -> None:
        min_val = self.getMin()
        if min_val is None or min_val > val:
            min_val = val

        self.st.append([val, min_val])

    def pop(self) -> None:
        self.st.pop()

    def top(self) -> int:
        return self.st[-1][0] if self.st else None

    def getMin(self) -> int:
        return self.st[-1][1] if self.st else None


# Your MinStack object will be instantiated and called as such:
# obj = MinStack()
# obj.push(val)
# obj.pop()
# param_3 = obj.top()
# param_4 = obj.getMin()


if __name__ == "__main__":
    minStack = MinStack()
    minStack.push(-2)
    minStack.push(0)
    minStack.push(-1)
    minStack.getMin()
    minStack.top()
    minStack.pop()
    minStack.getMin()