如何只打印一次递归调用中的语句？ Python

Question

def recur(y):
    if y>0:
        print(y)
        recur(y-1)
        print("all the recursive calls are done, now printing the stack")   # I want this statement printed only once
        print(y)
recur(5)

I want the print statement to be printed only once. I don't want to use if y>4 print() that defect the purpose.

I want the output to be like this:

5
4
3
2
1
all the recursive calls are done, now printing the stack
1 
2
3
4
5

Answer 1

Put the message in the else: block so it's only printed when we don't recurse.

def recur(y):
    if y>0:
        print(y)
        recur(y-1)
        print(y)
    else:
        print("all the recursive calls are done, now printing the stack")

recur(5)

Answer 2

when you reach the stop condition print the required text:

def recur(y):
    if y>0:
        print(y)
        recur(y-1)      
        print(y)
    else:
        print("all the recursive calls are done, now printing the stack")

Answer 3

def recur(y):
    if y > 0:
        print(y)
        recur(y - 1)
        if y == 1:
            print("all the recursive calls are done, now printing the stack")   # I want this statement printed only once
        print(y)


recur(5)

prints

5
4
3
2
1
all the recursive calls are done, now printing the stack
1
2
3
4
5

because it only prints at the end of recursion, where y == 1. If you do recursion where 1 isn't the end, all you need to do to create a similar effect is to locate where the final recursion is and then put a print statement in that will only activate if you're in the final recursion.