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();
*/