where the function has problem? n = 900 is OK , but n = 1000 is ERROR

Steven D'Aprano steve+comp.lang.python at pearwood.info
Mon Aug 1 11:19:30 CEST 2011


jc wrote:

> # Get Fibonacci Value
> #    Fibonacci(N) = Fibonacci(N-1) + Fibonacci(N-2)
> #
> # n = 900 is OK
> # n = 1000 is ERROR , Why

How should we know? Please tell us what the error is, don't expect us to
guess.


[...]
> if __name__ == '__main__':
> # This n = 900 is OK
> # But n = 1000 is ERROR

Hint: how big is the cache? If the cache has 900 items, what makes you think
you can look up the 1000th item?

>     n = 900
>     cache = range(0 , n + 1 , 1)
>     for i in cache:
>         cache[i] = -1

This is a waste of time. Better to write:

cache = [-1]*900

Even better is to use a dict instead of a list.



-- 
Steven




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