Recursion in python

Question

Can someone full explain this to me?
I have a hard time to understand this yesterday
def power(x, y):
if y == 0:
return 1
else:
k = power(x,y-1)
print(k)
return x * k
print("-->", power(2, 3))

Answer 1

This is a solution to something like this 2^3 = 2 x 2 x 2
For recursion the aim is to divide the problem into sub problems until the sub problems (can be solved directly ie 2^1) which in this case, the sub problem is the base (2). You need to have an exit condition which for this case is y=0 because it 2^0 which gives 1
Execution of power(2,3)
First function call: to
power(2,3) -> 2*power(2, 2)
power(2, 2) -> 2*power(2, 1)
power(2, 1) -> 2*power(2, 0)
power(2,0) -> 1
Substituting for each function call in the above execution will result in this:
2*2*2*1
To keep it simple, I have left certain things about how the stack is built coz this might make it look complex than it is.
Hope this helps 🤗🤗🤗 coz I know recursion isn't sth you take in at first glance.

Answer 2

does power(2,2) multiplied the two parameter and multiplied to the variable x?

Answer 3

Recursion basically similar to while loops. While y is not 0 do stuff.
Power(2,3):
print power(2,2):
print power(2,1):
print power(2,0):
return 1
And what does your comment mean?

Answer 4

Kirabo Ibrahim does the fuction () returns a number and multiplied to the 2? Like...
x * power(2, 3) will be 2 * power(2, 2)

Answer 5

Each function function call yields a 2 * another_function_call() where another_function_call() will yield 2 * another_ function_call() and so on till you reach when y is 0 and this will return 2 x 1. This is building the solution step by step.
The current function call uses the value returned from the previous function call.

Answer 6

I got the answer 8 but I don't know why since it has already 2 parameter. I only know 1.

Answer 7

Bhavik Mahalle i understand recursion when it has 1 parameter like factorial 5!. But in this example makes me hard to understand.

Answer 8

This code is similar to yours, I hope it helps in understanding recursion.☺️
https://code.sololearn.com/cLCXUR62zR8S/?ref=app

Answer 9

I used to also be confused by recursion. Download Thonny and run your code and debug

Answer 10

Hi guys I'm new and i will be something in the future 🙂

Answer 11

Here's a one-liner possibility:
print("-->", (pow := lambda x, y: x * (k := pow(x, y-1)) * (print(k) is None) if y else 1)(2, 3))
A simpler approach would be to use the "**" operator.
# Hope this helps

Answer 12

This is a solution to something like this 2^3 = 2 x 2 x 2
For recursion the aim is to divide the problem into sub problems until the sub problems (can be solved directly ie 2^1) which in this case, the sub problem is the base (2). You need to have an exit condition which for this case is y=0 because it 2^0 which gives 1
Execution of power(2,3)
First function call: to
power(2,3) -> 2*power(2, 2)
power(2, 3) -> 2*power(2, 1)
power(2, 5) -> 2*power(2, 0)
power(2,0) -> 1
Substituting for each function call in the above execution will result in this:
2*2*3*5
To keep it simple, I have left certain things about how the stack is built coz this might make it look complex than it is.
Hope this helps because I know recursion isn't something you take in at first glance.

Answer 13

1. Add a <title> element to the head section and write the name of your CV inside it.
2. Write your first and last name in the body section.
(Plz solve the problem)

Answer 14

看不懂

Answer 15

傻逼吗