剑指 Offer 59

class MaxQueue {
        Queue<Integer> queue;
        LinkedList<Integer> max;
        public MaxQueue() {
            queue = new LinkedList<>();
            max = new LinkedList<>();
        }

        public int max_value() {
            return max.size() == 0?-1:max.getFirst();
        }

        public void push_back(int value) {
            queue.add(value);
            while(max.size()!=0&&max.getLast()<value){
                max.removeLast();
            }
            max.add(value);
        }

        public int pop_front() {
            if(max.size()!=0&&queue.peek().equals(max.getFirst())){
                max.removeFirst();
            }
            return queue.size()==0?-1:queue.poll();
        }
    }