题目描述
定义栈的数据结构,请在该类型中实现一个能够得到栈中所含最小元素的min函数(时间复杂度应为O(1))。
思路
用辅助栈存储当前data的最小值,辅助栈头即为min值。
class MinStack(object):
def __init__(self):
self.stack = []
self.min_stack = []
def push(self, node):
# write code here
self.stack.append(node)
if not self.min_stack:
self.min_stack.append(node)
else:
if self.min_stack[-1] < node:
self.min_stack.append(self.min_stack[-1])
else:
self.min_stack.append(node)
def pop(self):
# write code here
self.stack.pop(-1)
self.min_stack.pop(-1)
def top(self):
# write code here
if self.stack:
return self.stack[-1]
else:
return []
def min(self):
# write code here
return self.min_stack[-1]