I’m trying to learn code with Programiz; the challenge is to find and print the numbers in a Fibonacci sequence that are less than the number you input. Here is the code, and so far it works for inputting 5 and 6. With both of those inputs, it stops at 3 and 5, respectivly, in the sequence, but any number higher than that and it keeps going. I can’t figure out why. I tried to follow the loop manually. If I input 7, it should loop 6 times (the range is 1, 7, but it stops at 7).
> loop 1=print t1(1), result=t1(1)+t2(1), t1=t2(1), t2=result(2)
> loop 2=print t1(1), result=t1(1)+t2(2), t1=t2(2), t2=result(3)
> loop 3=print t1(2), result=t1(2)+t2(3), t1=t2(3), t2=result(5)
> loop 4=print t1(3), result=t1(3)+t2(5), t1=t2(5), t2=result(8)
> loop 5=print t1(5), result=t1(5)+t2(8), t1=t2(8), t2=result(13)
shouldnt it stop here because t1=8 which is greater than n(7), closing the while loop
n = int(input())
t1 = 1
t2 = 1
result = 0
while t1<n:
for num in range (1,n):
print(t1)
result=t1+t2
t1=t2
t2=result
Sorry for the long question, I just figured I should explain my thought process on troubleshooting it, if anyone can help it would be appreciated.
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1
Your inner loop doesn’t have any constraint except to iterate from 1 to n-1.
If you input 7, that inner loop will run six times, even if that means t1 ends up larger than n.
Consider if we input 12. 89 is much larger than 12 but we keep going well past it. In fact, predictably, we see 11 iterations.
>>> t1 = 1
>>> t2 = 1
>>> result = 0
>>> while t1<n:
... for num in range (1,n):
... print(t1)
... result=t1+t2
... t1=t2
... t2=result
...
1
1
2
3
5
8
13
21
34
55
89
A very simple fix would be to include a conditional break from the inner loop.
n = int(input())
t1 = 1
t2 = 1
result = 0
while t1 < n:
for num in range(1, n):
if t1 >= n: break
print(t1)
result = t1 + t2
t1, t2 = t2, result