Ways to multiply n elements with an associative operation | Function to find the required factorial ; Function to find nCr ; Function to find the number of ways ; Driver code
function fact ( n ) { if ( n == 0 n == 1 ) return 1 ; let ans = 1 ; for ( let i = 1 ; i <= n ; i ++ ) ans = ans * i ; return ans ; } function nCr ( n , r ) { let Nr = n , Dr = 1 , ans = 1 ; for ( let i = 1 ; i <= r ; i ++ ) { ans = parseInt ( ( ans * Nr ) / ( Dr ) , 10 ) ; Nr -- ; Dr ++ ; } return ans ; } function solve ( n ) { let N = 2 * n - 2 ; let R = n - 1 ; return nCr ( N , R ) * fact ( n - 1 ) ; } let n = 6 ; document . write ( solve ( n ) ) ;