activity select problem(greedy algorithms)

 1 public class activity_select {
 2      int[] s = {1,3,0,5,3,5,6,8,8,2,12};
 3     int[] f = {4,5,6,7,9,9,10,11,12,14,16};
 4     private static class activity{
 5         private int sta ;
 6         private int fin ;
 7         public activity(){
 8             sta = 0;
 9             fin = 0;
10         }
11     }
12 
13     public   activity[] select(){
14     activity[]  act = new activity[s.length];
15     for(int i = 0;i<s.length;i++){   //initial
16         act[i] = new activity();
17         act[i].sta = s[i];
18         act[i].fin = f[i];
19     }    
20     for(int i = 0;i<s.length;i++){   //insert sort from early fin to later fin
21         for(int j = i;j < s.length;j++){
22             if(act[i].fin > act[j].fin){
23                 int testa = act[j].sta;
24                 int tefin = act[j].fin;
25                 act[j].sta = act[i].sta;
26                 act[j].fin = act[i].fin;
27                 act[i].fin = tefin;
28                 act[i].sta = testa;
29             }
30         }
31     }    
32     activity[] res = new activity[s.length];
33     res[0] = act[0];
34     int j = 0;
35     for(int i = 0;i < s.length -1;i++){
36         if(act[i+1].sta > res[j].fin){
37             res[++j] = act[i + 1];
38         }
39     }
40     activity[] res1 = new activity[j+1];
41     for(int i = 0;i <=j;i++){
42         res1[i] = res[i];
43     }
44     return res1;
45     }
46     
47     
48 
49     public static void main(String[] args){
50         activity_select  ac = new activity_select();
51         activity[] a = ac.select();
52         int n = a.length;
53         for(int i = 0;i < n;i++){
54             System.out.println(a[i].sta + " " +a[i].fin);
55         }
56     }
57     
58     
59 }