【leetcode 设计题 C++】剑指 Offer 59 - II. 队列的最大值

剑指 Offer 59 - II. 队列的最大值

class MaxQueue {
public:
    queue<int> Q;
    deque<int> maxQ;
    MaxQueue() {
    }
    
    int max_value() {
        return maxQ.empty() ? -1 : maxQ.front();
    }
    
    void push_back(int value) {
        Q.push(value);
        while(!maxQ.empty() && value > maxQ.back()) maxQ.pop_back();
        maxQ.push_back(value);
    }
    
    int pop_front() {
        if(Q.empty()) return -1;
        int ans = Q.front();
        Q.pop();
        if(maxQ.front() == ans) maxQ.pop_front();
        return ans;
    }
};

/**
 * Your MaxQueue object will be instantiated and called as such:
 * MaxQueue* obj = new MaxQueue();
 * int param_1 = obj->max_value();
 * obj->push_back(value);
 * int param_3 = obj->pop_front();
 */