[“RecentCounter”,“ping”,“ping”,“ping”,“ping”,“ping”]
[[],[1],[100],[3001],[3002],[6666]]

输出的是 [null,1,2,3,3,3]
预期的是 [null,1,2,3,3,1]

非要用队列，写个递归

var RecentCounter = function() {
    this.q = [];
};

/** 
 * @param {number} t
 * @return {number}
 */
RecentCounter.prototype.ping = function(t) {
    this.q.push(t);

    let shiftFn = () => {
        if(this.q[0] >= t - 3000) return;
        this.q.shift();
        shiftFn()
    }
   shiftFn();

    return this.q.length
};

/**
 * Your RecentCounter object will be instantiated and called as such:
 * var obj = new RecentCounter()
 * var param_1 = obj.ping(t)
 */