题解 | 牛牛的Ackmann

import sys
sys.setrecursionlimit(1000000)      # python得限制递归深度
n, m = map(int, input().split(' '))
def ackmann(m,n):
    if m == 0:
        return n+1
    elif m > 0 and n == 0:
        return ackmann(m-1,1)
    elif m > 0 and n > 0:
        return ackmann(m-1,ackmann(m,n-1))
print(ackmann(m,n))