array to store prefix count of zeros from right to left for booleanean array
let p_arr = new Array ( n ) ; for ( let i = 0 ; i < n ; i ++ ) { p_arr [ i ] = new Array ( n ) ; for ( let j = 0 ; j < n ; j ++ ) p_arr [ i ] [ j ] = 0 ; } findPrefixCount ( p_arr , set_bit ) ;