Sort 3 numbers array

Sort 3 numbers array

Sort an array which has values 1, 2 and 3 with n comparisons only.
input : {1,2,3,2,3,1,2,3,3,2,2,2,3,1,2,1,1,3,3,2,2,1,2,2,3,2,2,2,1,3,1}
output: 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3

Sol:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53

// Sort an array which has numbers 1, 2 and 3 int[] Sort(int[] a) {     int i,j;     for(i=0,j=a.length-1; i<j;)     {         if(a[i]==1)         {             i++;         }         else if(a[j]==3)         {             j--;         }         else if(a[i]>a[j] && a[i]==3)         {                            Swap(a,i,j);         }         else if(a[i]>a[j] && a[j]==1)         {             Swap(a,i,j);         }         else         {          // both values are 2             int k=i+1;             while(a[k]==a[j] && k<j)             {                 k++;             }             if(j==k)                 break;             else if(a[k]<a[i] && a[k]==1)             {                 Swap(a,k,i);                 i++;             }             else if(a[k]>a[j]&&a[k]==3)             {                 Swap(a,k,j);                 j--;             }                       }               }     return a; }   void Swap(int[] a, int i, int j) {     int temp=a[i];     a[i]=a[j];     a[j]=temp; }