Returns value of Binomial Coefficient C ( n , k )
function nCr ( n , k ) { let C = new Array ( n + 1 ) ; for ( let i = 0 ; i <= n ; i ++ ) { C [ i ] = new Array ( k + 1 ) ; for ( let j = 0 ; j <= k ; j ++ ) { C [ i ] [ j ] = 0 ; } } let i , j ;