Which is better way to calculate nCr

Question

Approach 1:
C(n,r) = n!/(n-r)!r!

Approach 2:
In the book Combinatorial Algorithms by wilf, i have found this:
C(n,r) can be written as C(n-1,r) + C

Answer 1

unsigned long long ans = 1,a=1,b=1;
        int k = r,i=0;
        if (r > (n-r))
            k = n-r;
        for (i = n ; k >=1 ; k--,i--)
        {
            a *= i;
            b *= k;
            if (a%b == 0)
            {
                a = (a/b);
                b=1;
            }
        }
        ans = a/b;