Problem

Write a class RecentCounter to count recent requests.

It has only one method: ping(int t), where t represents some time in milliseconds.

Return the number of pings that have been made from 3000 milliseconds ago until now.

Any ping with time in [t - 3000, t] will count, including the current ping.

It is guaranteed that every call to ping uses a strictly larger value of t than before.

Example 1:

Input: inputs = [“RecentCounter”,”ping”,”ping”,”ping”,”ping”], inputs = [[],[1],[100],[3001],[3002]]

Output: [null,1,2,3,3]

Note:

Each test case will have at most 10000 calls to ping.

Each test case will call ping with strictly increasing values of t.

Each call to ping will have 1 <= t <= 10^9.

Pre analysis

Will keep an array to keep each pings and return filter where currentPing-indexedPing <=3000

Post analysis

After few submission, since test cases were increasing size of array, it took ~5 sec for 68 test cases. Realised that array could be trimmed since no new ping would satisfy previous ping conditions. This resulted for timing to 170ms approx.

Another solution

Better and clean solution with shift

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

/**
* @param {number} t
* @return {number}
*/
RecentCounter.prototype.ping = function(t) {
this.queue.push(t);
    while(this.queue.length && this.queue[0] < t-3000) {
        this.queue.shift();
    }
    return this.queue.length;
};