26 lines
409 B
PHP
26 lines
409 B
PHP
<?php
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/*
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* Gnieark's anwser to euler problem 25
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* https://projecteuler.net/problem=25
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*/
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//see https://fr.wikipedia.org/wiki/Suite_de_Fibonacci#Avec_la_formule_de_Binet
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echo intval((log(10)*999 + (log(5)/2) ) / log(1.61803398875)) +1;
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/*
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Very long solution that didn't test :
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$i=1;
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$j=2;
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$count=2;
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while(strlen($i)<1000){
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$new=gmp_add($i,$j);
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$i=$j;
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$j=$new;
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$count++;
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}
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echo $count;
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*/ |