Hal Lawrence - 4 months ago 32

Python Question

What I am trying to do is count the steps when given a positive int x until it ends at 1. then if its an even number, divide in half to get the next int and if its odd, multiply it by 3 & add 1 to get the next int. But it will always break at 1. I'm getting an error on line 3 "TypeError: 'int' object is not iterable," and its been bothering me. Any advice/fixes appreciated.

Example test: collatz_counts(4) → 3 # 4 -> 2 -> 1 (3 steps)

Code I have:

`def collatz_counts(x):`

num = 0

for i in (x):

if i == 1:

num += 1

return num

elif i % 2 == 0:

num(i) / 2

num += 1

num.append(i)

else:

num = (i*2) + 3

num += 1

num.append(i)

return num

Answer

Use a while loop. Just modify `x`

in place until you get to `1`

and keep track of the number of `steps`

each time you run a cycle.

```
def collatz_counts(x):
steps = 0
while x != 1:
if x % 2:
x = x * 3 + 1
else:
x = x // 2
steps += 1
return steps
```