1 void swap(char[] a, int i, int j) 2     { 3         char tmp = a[i]; 4         a[i] = a[j]; 5         a[j] = tmp; 6     } 7      8     void Perm(char[] a, int from, int to) 9     {10         if(to <=1 )11             return;12         if(from == to)13         {14             for(int i = 0; i <= to; i++)15                 System.out.print(a[i]);16             System.out.println();17         }18         else19         {20             for(int j = from; j <= to; j++)21             {22                 swap(a, j, from);23                 Perm(a, from+1, to);24                 swap(a, j, from);25             }26         }            27     }