[7]力扣每日一题

题目呈现如下:

比较简单,直接上代码.

下附AC代码:

// 采用辅助栈
// 我们需要保存最新的最小值,同时能够保存上个最小值以及上上个最小值..
// 符合FILO(先进后出,后进先出)原则,所以我们也同样用栈来记录最小值
class MinStack {
public:
    /** initialize your data structure here. */
    stack<int> s;
    stack<int> min_s;
    MinStack() {
        min_s.push(INT_MAX);
    }
    
    void push(int x) {
        s.push(x);
        int cur_min = min_s.top();
        if(x<=cur_min) min_s.push(x);
    }
    
    void pop() {
        int toPop = s.top();
        s.pop();
        int cur_min = min_s.top();
        if(toPop == cur_min) min_s.pop();
    }
    
    int top() {
        return s.top();
    }
    
    int getMin() {
        return min_s.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();
 */