155. 最小栈

思路

按栈的特点：顶部即列表尾部

class MinStack(object):def __init__(self):self.stack=[]def push(self, val):""":type val: int:rtype: None"""self.stack.append(val)def pop(self):""":rtype: None"""self.stack.pop()def top(self):""":rtype: int"""return self.stack[-1]def getMin(self):""":rtype: int"""return min(self.stack)# 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()