执行基本案例时，它会打印值，但返回None

Question

``##当基本案例在递归终止时执行时，代码需要返回接收者的值 import math days = int(input()) def adv(days,recipient,likes,depth): depth+=1 print(" "*depth + "adv({},{})at day {} and likes are {}".format(days-4,recipient,days,likes)) days -= 1 if days == 0: #print(recipient) print(likes) #print(" "*depth + "adv({},{})at day {} and likes are {}".format(days-4,recipient,days,likes)) ，在这里它返回接收者`         返回收件人     其他：         点赞=点赞+ math.floor（接收者/ 2）         adv（天数，数学。底数（收件人/ 2）* 3，喜欢的深度）

＃该变量a应该接收到接收者的值，但

a = adv（天+1,5,0,1）

打印（a）

它返回None

Answer 1

这是因为它打算用作递归函数，但是当您从内部调用它时，您不会返回该调用。相反，当从内部调用时，最里面的返回值将被丢弃，并且None将被传递并由原始调用返回。您可以这样修复它：

import math
days = int(input())
def adv(days,recipient,likes,depth):
    depth+=1
    print(" "*depth + "adv({},{})at day {} and likes are {}".format(days-4,recipient,days,likes))
    days -= 1
    if days == 0:
        return recipient
    else:
        likes =likes+ math.floor(recipient/2)
        return adv(days,math.floor(recipient/2)*3,likes,depth) #<------

a= adv(days+1,5,0,1)
print(a)

输出：

5
  adv(2,5)at day 6 and likes are 0
   adv(1,6)at day 5 and likes are 2
    adv(0,9)at day 4 and likes are 5
     adv(-1,12)at day 3 and likes are 9
      adv(-2,18)at day 2 and likes are 15
       adv(-3,27)at day 1 and likes are 24
27