text: Sort the input array , the array is assumed to have values in { 0 , 1 , 2 }
code: void sort012 ( int a [ ] , int arr_size ) { int lo = 0 ; int hi = arr_size - 1 ; int mid = 0 ; while ( mid <= hi ) { switch ( a [ mid ] ) { case 0 : swap ( & a [ lo ++ ] , & a [ mid ++ ] ) ; break ; case 1 : mid ++ ; break ; case 2 : swap ( & a [ mid ] , & a [ hi -- ] ) ; break ; } } }