Recursive Function

Question

Can someone please describe this recursive function:

def power(x, y):
if y == 0:
return 1
else:
return x * power(x, y-1)

print(power(2, 3))

Thank you

Answer 1

This function do exponentials

Like power(2,3)=8

When call it in the first time assume that y=3 and x=2

y==0 #false
Goto else
2*power(2,2)

Goto second call

y==0 #false
Goto else
2*power(2,1)

Goto third call

y==0 #true
Return 1

Which means

2*power(2,2)

And that's equal to

2*(2*power(2,1)) #the value of power(2,2)

And that's equal to

2*(2*(2*power(2,0))) #the value of power(2,1)

And the value of power(2,0) is 1

And that's is... According to the previous calculations

2*2*2*1 which equal to 8

Answer 2

Whenever the function gets called i.e., power(2,3) [here] control goes to function... Enters into the function and starts executinh the stmts we have written... There you given two conditions... If y==0, this got failed and control now goes to else part.. There you have given return x*power(x, y-1) which is a recursive function... Until the y value equals to zero, it will get executed repeatedly...
Simply,
First time: x*power(x, y-1) = 2*power(2,2)
second time: now, y value equals to 2
So, 2*2*power(2,1)
Third time: now, y value equals to 1
So, 2*2*2*power(2,0)
Fourth time : y value became 0
So,if Condiction is true and returns 1 so, y became 1
So,finally
2*2*2*2 which is equal to 8

Answer 3

2 * power(2, 2)
2 * power(2, 1)
2 * 1

2*2*2*1 = 8