leetcode栈的最小值

1.双栈

一个栈保存元素，一个栈保存最小值

代码如下：

class MinStack {
    
    stack<int> data;
    stack<int> minstack;
public:
    /** initialize your data structure here. */
    MinStack() {
       // data=new stack<>();
       // minstack=new stack<>();
    }
    
    void push(int x) {
        data.push(x);
        if(minstack.empty()||x<minstack.top())//最小栈为空或当前元素小于栈顶元素
          minstack.push(x);
        else
          minstack.push(minstack.top()); 
    }
    
    void pop() {
        data.pop();
        minstack.pop();
    }
    
    int top() {
        return data.top();
    }
    
    int getMin() {
        return minstack.top();
    }
};

/**
 * Your MinStack object will be instantiated and called as such:
 * MinStack* obj = new MinStack();
 * obj->push(x);
 * obj->pop();
 * int param_3 = obj->top();
 * int param_4 = obj->getMin();
 */

2.