**933. 最近的请求次数（队列入门）**

class RecentCounter {
    Deque<Integer> queue;
    public RecentCounter() {
        queue = new ArrayDeque<>();
    }
    
    public int ping(int t) {
        while(!queue.isEmpty() && t - queue.peekFirst() > 3000) {
            queue.removeFirst();
        }
        queue.addLast(t);
        return queue.size();
    }
}

**649. Dota2 参议院（贪心+两个队列）**

思路：将不同阵营放到不同队列里面去，然后依次比较队首。

class Solution {
    public String predictPartyVictory(String senate) {
        int size = senate.length();
        Deque<Integer> dd = new ArrayDeque<>();
        Deque<Integer> dr = new ArrayDeque<>();

        char[] chars = senate.toCharArray();

        for(int i = 0; i < size; i++) {
            if(chars[i] == 'D') dd.addLast(i);
            else dr.addLast(i);
        }

        while(!dd.isEmpty() && !dr.isEmpty()) {
            int ld = dd.peekFirst(), lr = dr.peekFirst();
            if(ld < lr) {
                dd.addLast(ld + size);
            }else {
                dr.addLast(lr + size);
            }
            dr.removeFirst();
            dd.removeFirst();
        }

        if(dd.isEmpty()) return "Radiant";
        return "Dire";
    }
}