这三种冒泡排序的区别

Question

for ( i = 0 ; i < n - 1 ;  i ++){        for ( j = i + 1 ; j < n ; j ++){                if ( a[ i ] > a[ j ])                        swap( a[ i ] , a[ j ]);        }    }----------------------------------------for ( i = 0 ; i < n - 1 ;  i ++){        for ( j = 0 ; j < n - i - 1 ; j ++){                if ( a[ j ] > a[ j + 1 ])                        swap( a[ j ] , a[ j + 1 ]);        }    }-----------------------------------------for ( i = 0 ; i < n - 1 ;  i ++){        for ( j = n - 1 ; j > i ; -- j ){                if ( a[ i ] > a[ j ])                        swap( a[ i ] , a[ j ]);        }    }

Answer 1

哪一种最优？