def func(x,y): if x < 0 or y < 0: return 0 elif x == 0 or y == 0: return 1 else: return func(x-1, y)+func(x, y-1) while True: try: a,b = map(int,input().split()) c = func(a, b) print(c) except: break 采用递归算法,求解即可