Question

How to find the sum of the even valued in fibonacci sequence with PHP

Answer 1

function sumEvenNumbersInFibonacci($n) {
    if ($n < 1) {
        return 0;
    }

    echo "0 1 ";

    $currentNumber = 0;
    $nextNumber = 1;
    $sum = 0;

    for ($i = 0; $i < $n - 2; $i++) {
        $temp = $nextNumber;
        $nextNumber = $currentNumber + $nextNumber;
        $currentNumber = $temp;
        echo $nextNumber . " ";

        if ($nextNumber % 2 == 0) {
            $sum += $nextNumber;
        }
    }

    return $sum;
}

$limit = 15;

// Calculate and print the result
$sumResult = sumEvenNumbersInFibonacci($limit);
echo "\nSum = " . $sumResult;



/*
run:

0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 
Sum = 188

*/

 

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