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Re: Read file text and find fibonacci series

by haukex (Abbot)
on Dec 28, 2017 at 19:12 UTC ( #1206352=note: print w/replies, xml ) Need Help??


in reply to Read file text and find fibonacci series

This appears to have been posted to Meditations, but I'm not sure if you meant it to be a question? Anyway, you're describing scanning a string looking for a pattern, which is exactly what regular expressions are good at. Ignoring the duplicate 1's, there are only 29 Fibonacci numbers with 1 to 6 digits, a regex can handle that just fine (and it would have no problem handling much more). See Building Regex Alternations Dynamically.

Update: You appear to have edited your node to remove its content, please see How do I change/delete my post? for why you shouldn't do that. Content restored, thanks Athanasius. Also made very minor fixups.

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Re^2: Read file text and find fibonacci series
by vr (Friar) on Jan 03, 2018 at 00:01 UTC

    Hi, haukex.

    while (/(?=($re))./g) { ... }

    "Look for a fib anywhere ahead, then if found, consume its leftmost digit, then repeat" probably makes no sense, even for this assignment/homework. The %fib was built but not actually used. The "3 element" part of assignment (not addressed in your code) could be either consecutive, or just ascending fibs. But, the way %fib was constructed, it may be to help looking for a fib whose initial digits are a fib too, whose initial digits, ..., etc. While leftmost digit of any 2-digit fib is a fib, -- I wonder if any value of %fib could be an array with more than 3 elements? :)

    P.S. Please, I'm not appealing to rewrite anything, don't waste your time, the task is too much unclear.

    P.P.S. And, I suspect the "PERFECT SQUARE" in OP, in C, won't work for 6-digit numbers and int type, because of overflow?

      The %fib was built but not actually used.

      Well not quite, it is used for what you said:

      to help looking for a fib whose initial digits are a fib too

      This is what I was using it for, since I didn't feel like getting too fancy with the regex. The code I wrote was mostly just an implementation of my interpretation of the description the OP gave:

      "Check 4 is fibonacci number , no , go ahaed 49 is fibonacci number , no, next 496 is fibonacci ,no, 4969 after 44693 [sic] ,after 496934 no.There isnt any fibonacci , go to next digit and do it again 9 , 96,969,9693,96934."
      I wonder if any value of %fib could be an array with more than 3 elements?

      Good question, I didn't try cranking up $DIGITS past 60 yet...

      the task is too much unclear

      Agreed, which is why I just implemented the part I (thought I) understood ;-)

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