minStack.py

#Time Complexity = O(1) 
#Space Complexity = O(n)


from collections import deque

class MinStack:

    def __init__(self):
        self.mainStack = deque()
        self.minStack = deque()
        

    def push(self, val: int) -> None:
        self.mainStack.append(val)
        
        if not self.minStack:
            self.minStack.append(val)
        else:
            if self.minStack[-1] >= val:
                self.minStack.append(val)
        

    def pop(self) -> None:
        topElement = self.mainStack.pop()
        if topElement == self.minStack[-1]:
            self.minStack.pop()
        return topElement
        

    def top(self) -> int:
        return self.mainStack[-1]
        

    def getMin(self) -> int:
        return self.minStack[-1]
        


# 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()