CP-Snippets

fac

• fac

• https://thesobersobber.github.io/CP-Snippets/fac
  

• github-snip-file

int fac[maxn];
int inv[maxn];
fac[1] = inv[1] = 1;
for (int i=2; i<maxn; i++){
  fac[i] = (fac[i-1] * i)%mod;
  inv[i] = power(fac[i], mod - 2);
}