包含min函数的栈

class MinStack {
public:
    /** initialize your data structure here. */
    stack<int> stk, stk_min; //定义
    MinStack() {
        
    }
    
    void push(int x) {
        stk.push(x);
        if (stk_min.size()) {
            x = min(x, stk_min.top());
        }
        stk_min.push(x);
        //cout << stk.top() << " " << stk_min.top() << endl;
    }
    
    void pop() {
        if (stk.size()) {
            stk.pop();
        }
        if (stk_min.size()) {
            stk_min.pop();
        }
    }
    
    int top() {
         return stk.top();
    }
    
    int getMin() {
        return stk_min.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();
 */