LeetCode:Min Stack(待更新)

最新推荐文章于 2019-01-13 06:57:13 发布

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最新推荐文章于 2019-01-13 06:57:13 发布

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原文链接：http://www.cnblogs.com/xiaoying1245970347/p/4702143.html

本文介绍了一个设计栈的数据结构，该栈能够支持入栈、出栈、获取顶部元素以及在常数时间内获取最小元素的操作。通过维护两个栈来实现这一目标。

Design a stack that supports push, pop, top, and retrieving the minimum element in constant time.

push(x) -- Push element x onto stack.
pop() -- Removes the element on top of the stack.
top() -- Get the top element.
getMin() -- Retrieve the minimum element in the stack.

class MinStack {
private:  
    std::stack<int> stack;  
    std::stack<int> min_stack;  
public:  
    void push(int x) {  
        stack.push(x);  
        if (min_stack.empty() || ((!min_stack.empty()) && x <= min_stack.top())) {  
            min_stack.push(x);  
        }  
    }  
      
    void pop() {  
        if (!stack.empty()) {  
            if (stack.top() == min_stack.top())  
                min_stack.pop();  
            stack.pop();  
        }  
    }  
      
    int top() {  
        if (!stack.empty())  
            return stack.top();  
    }  
      
    int getMin() {  
        if (!min_stack.empty())  
            return min_stack.top();  
    }  
};