question: private void sort ( int off , int len ) { if ( len < 7 ) { for ( int i = off ; i < len + off ; i ++ ) { for ( int j = i ; j > off && x [ j - 1 ] > x [ j ] ; j -- ) { swap ( j , j - 1 ) ; } } return ; } int m = off + ( len > > 1 ) ; if ( len > 7 ) { int l = off ; int n = off + len - 1 ; if ( len > 40 ) { int s = len / 8 ; l = med3 ( l , l + s , l + 2 * s ) ; m = med3 ( m - s , m , m + s ) ; n = med3 ( n - 2 * s , n - s , n ) ; } m = med3 ( l , m , n ) ; } long v = x [ m ] ; int a = off , b = a , c = off + len - 1 , d = c ; while ( true ) { while ( b <= c && x [ b ] <= v ) { if ( x [ b ] == v ) { swap ( a ++ , b ) ; } b ++ ; } while ( c >= b && x [ c ] >= v ) { if ( x [ c ] == v ) { swap ( c , d -- ) ; } c -- ; } if ( b > c ) { break ; } swap ( b ++ , c -- ) ; } int s , n = off + len ; s = Math . min ( a - off , b - a ) ; vecswap ( off , b - s , s ) ; s = Math . min ( d - c , n - d - 1 ) ; vecswap ( b , n - s , s ) ; if ( ( s = b - a ) > 1 ) { sort ( off , s ) ; } if ( ( s = d - c ) > 1 ) { sort ( n - s , s ) ; } }
target:  Sorts the arrays in the given range. 