kangaroo.php

<?php

/*
 * Complete the 'kangaroo' function below.
 *
 * The function is expected to return a STRING.
 * The function accepts following parameters:
 *  1. INTEGER x1
 *  2. INTEGER v1
 *  3. INTEGER x2
 *  4. INTEGER v2
 */

function kangaroo($x1, $v1, $x2, $v2)
{
    if ($x1 < $x2 && $v1 > $v2) {
        while ($x1 < $x2) {

            $x1 += $v1;
            $x2 += $v2;
            if ($x1 === $x2) {
                return 'YES';
            }
        }
    } elseif ($x1 > $x2 && $v1 < $v2) {
        while ($x1 > $x2) {
            $x1 += $v1;
            $x2 += $v2;
            if ($x1 === $x2) {
                return 'YES';
            }
        }
    }

    return 'NO';
}

echo kangaroo(0, 2, 5, 3);