text: Array to store required prefix count of 1 s from right to left for boolean array
code: int p_arr [ ] [ ] = new int [ n ] [ n ] ; for ( int i = 0 ; i < n ; i ++ ) for ( int j = 0 ; j < n ; j ++ ) p_arr [ i ] [ j ] = 0 ; findPrefixCount ( p_arr , set_bit ) ;