Design Hit Counter

 1 public class HitCounter {
 2     private int[] count;
 3     private int[] indexes;
 4 
 5     /** Initialize your data structure here. */
 6     public HitCounter() {
 7         count = new int[300];
 8         indexes = new int[300];
 9         for (int i = 0; i < 300; i++) {
10             indexes[i] = i;
11         }
12     }
13     
14     /** Record a hit.
15         @param timestamp - The current timestamp (in seconds granularity). */
16     public void hit(int timestamp) {
17         int index = timestamp % 300;
18         if (timestamp != indexes[index]) {
19             indexes[index] = timestamp;
20             count[index] = 0;
21         }
22         count[index]++;
23     }
24     
25     /** Return the number of hits in the past 5 minutes.
26         @param timestamp - The current timestamp (in seconds granularity). */
27     public int getHits(int timestamp) {
28         int result = 0;
29         for (int i = 0; i < 300; i++) {
30             result += timestamp - indexes[i] < 300 ? count[i] : 0;
31         }
32         return result;
33     }
34 }
35 
36 /**
37  * Your HitCounter object will be instantiated and called as such:
38  * HitCounter obj = new HitCounter();
39  * obj.hit(timestamp);
40  * int param_2 = obj.getHits(timestamp);
41  */