leetcode\HappyNumber::isHappy()

Complexity

Conditions	4
Paths	2

Size

Total Lines	23
Code Lines	16

Duplication

Lines	0
Ratio	0 %

Importance

Changes	1
Bugs	0	Features	0

<?php
    public static function isHappy(int $n): bool
    {
        if ($n <= 0) {
            return false;
        }
        $helper = static function (int $num) {
            [$sum, $tmp] = [0, null];
            while ($num) {
                $tmp = $num % 10;
                $sum += $tmp * $tmp;
                $num /= 10;
            }
            return $sum;
        };

        $slow = $fast = $n;
        do {
            $slow = $helper($slow);
            $fast = $helper($fast);
            $fast = $helper($fast);
        } while ($slow !== $fast);

        return $slow === 1;
    }