剑指offer--面试题21：包含min函数的栈

题目描述

# -*- coding:utf-8 -*-
class Solution:
    def __init__(self):
        self.stack = []
        self.minStack = []
         
    def push(self, node):
        # write code here
        self.stack.append(node)
        if len(self.minStack)>0:
            node = min(node, self.minStack[-1])
        self.minStack.append(node)
             
    def pop(self):
        # write code here
        #原题意不返回
        if len(self.stack):
            self.minStack.pop()
            self.stack.pop()
         
    def top(self):
        # write code here
        if len(self.stack):
            return self.stack[-1]
        return None
     
    def min(self):
        # write code here
        if len(self.minStack):
            return self.minStack[-1]
        return None

class Solution {
private:
    vector<int> stack;
    vector<int> minStack;
public:
    void push(int value) {
        stack.push_back(value);
        if(!minStack.empty()){
            int top = minStack.back();
            value = std::min(top, value);
        }
        minStack.push_back(value);
    }
     
    void pop() {
        if(!stack.empty()){
            stack.pop_back();
            minStack.pop_back();
        }
    }
     
    int top() {
        if(!stack.empty()){
            return stack.back();
        }
        return NULL;
    }
    int min() {
        if(!minStack.empty()){
            return minStack.back();
        }
        return NULL;
    }
};