순열

def perm(n, k):
    if k == n:
        print(p)
        return
    else:
        for i in range(k, n):
            p[k], p[i] = p[i], p[k]
            perm(n, k+1)
            p[k], p[i] = p[i], p[k]

p = [1, 2, 3]
perm(3, 0)

def f(n, m, k):
    if n == k:
        print(p)
    else:
        for i in range(m):
            if u[i] == 0:
                u[i] = 1
                p[k] = arr[i]
                f(n, m, k+1)
                u[i] = 0

p = [0] * 3
arr = [1,2,3,4,5]
u = [0] * len(arr)
# mPn, 몇번째 수인지
f(3, 5, 0)