Lintcode 12. Min Stack (Medium) (Python)

Min Stack

Description:

Implement a stack with min() function, which will return the smallest number in the stack.

It should support push, pop and min operation all in O(1) cost.

Example

push(1)

pop() // return 1

push(2)

push(3)

min() // return 2

push(1)

min() // return 1

Notice

min operation will never be called if there is no number in the stack.

Code:

class MinStack:

    def __init__(self):
        # do intialization if necessary
        self.stack = []
    """
    @param: number: An integer
    @return: nothing
    """
    def push(self, number):
        # write your code here

        self.stack.append(number)

    """
    @return: An integer
    """
    def pop(self):
        # write your code here
        return self.stack.pop()
    """
    @return: An integer
    """
    def min(self):
        # write your code here
        return min(self.stack)