CODEWITHSUNDEEP
pythonpython-3.xlist-comprehension
The shape
The shape

Reputation: 359

Double for loop in list comprehension

I have a problem with this code:

num = 111
num_list = list(map(int, str(num)))
i=len(num_list)
t=2**(i-1)
answer = sum([x*(l**2) for x in reversed(num_list) for l in range(len(num_list))])
if answer % 5 == 0:
  print(answer, "is divisible by 5")
else:
  print(answer, "is not divisible by five")

Yes it does work if you test it but it gives me :

15 is divisible by 5

instead of:

7 is not divisible by 5

So basically what my code does is it takes a binary number and turns into decimal and tests whether or not the decimal is divisible by 5. Don't ask me how but I know there is some problem with my list comphrehension and my double for loop. Please help and thank you!

Upvotes: 1

Views: 215

Answers (2)

Tanner Stratford
Tanner Stratford

Reputation: 152

You could also do this as well:

num = 111
num_list = list(map(int, str(num)))
i=len(num_list)
t=2**(i-1)
answer = 0
for l in num_list:
  answer += l*t
  t=int(t/2)
if answer % 5 == 0:
  print(answer, "is divisible by 5")
else:
  print(answer, "is not divisible by five")

Upvotes: 2

not_speshal
not_speshal

Reputation: 23146

Your logic for converting binary to decimal is a bit off. Try this:

answer = sum([x*(2**l) for l, x in enumerate(reversed(num_list))])
>>> answer
7

Upvotes: 4

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