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40 lines
787 B
PHP
40 lines
787 B
PHP
<?php
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/**
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* Problem:
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*
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* Each new term in the Fibonacci sequence is generated by adding the previous
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* two terms. By starting with 1 and 2, the first 10 terms will be:
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*
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* 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
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*
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* By considering the terms in the Fibonacci sequence whose values do not
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* exceed four million, find the sum of the even-valued terms.
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*
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*
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* Answer:
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*
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* 4613732
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*
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*
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* @link https://projecteuler.net/problem=2
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*/
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/**
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* @return int
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*/
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function problem2(): int
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{
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$maxNumber = 4000000;
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$currNumber = 1;
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$nextNumber = 2;
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$answer = 0;
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while ($currNumber <= $maxNumber) {
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$answer += $currNumber % 2 == 0 ? $currNumber : 0;
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[$currNumber, $nextNumber] = [$nextNumber, $currNumber + $nextNumber];
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}
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return $answer;
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}
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