I am trying to calculate a GCD of 2 numbers, the following code block works fine, I am using recursion, but when I am trying to return a value I am not able to do so, return a results in None
def gcd(a,b):
if b == 0:
print a
return a # This is not working
else:
gcd(b,a%b)
XX = gcd(3, 5)
print (XX)
Output:
1
None
Your code
def gcd(a,b):
if b == 0:
print a
return a # This is not working
else:
gcd(b,a%b)
XX=gcd(3,5)
print (XX)
will not work, because you are missing the return statement in the line gcd(b,a%b). So it should be
def gcd(a,b):
if b == 0:
print a
return a
else:
return gcd(b,a%b)
print(gcd(12, 4))
By the way - if possible, don't code things yourself, use the predefined library:
from fractions import gcd
print(gcd(4, 12))
Your recursion will not work... you are missing a return statement and also the algorithm does not work...
This is what a recursive gcd could look like:
def gcd(a,b):
r = a % b
if r == 0:
return a
elif r == 1:
return 1
return gcd(b, r)
and here a non-recursive gcd:
def gcd(a, b):
while b:
a, b = b, a % b
return a
also note that you could just use math.gcd.
Noneis no explicitreturnstatement is executed.gcdneeds to be returned, Likereturn gcd(b,a%b)