Practice project

This project is a practice for me. I was reading the chapters Permutation and combinations. So I Just used the formulla here to get the permutations and combinations. I know python have built-in packages for these operations. But it was fun😄.

Factorial

n!=n×(n−1)×(n−2)×⋯×1
n!=n×(n−1)×(n−2)×⋯×1
Special case: 0!=10!=1

Permutation

P(n,r)=n!/(n−r)!
P(n,r)=n!/(n−r)!

Combination

C(n,r)=n!/[r!×(n−r)!]
C(n,r)=n!/[r!×(n−r)!]