用 PHP 语言解决鸡兔同笼问题

用 PHP 语言解决鸡兔同笼问题，设已知总头数为H，总脚数为Y，求鸡兔各有多少只？

<?php
function fn($h,$y) {
    $maxC = $h;
    $minC = ceil($y/4);
    $c = $minC;
    $r = false;
    for(; $c<$maxC; $c++)
    {
        $r = $h - $c;
        if(($c*2 + $r*4) == $y) return $c;
    }
    return false;
}
$chick = fn(10,26);
if(false == $chick){
    echo "输入有误";
}else{
    $rabbit = 10 - $chick;
    echo "鸡:{$chick},兔:{$rabbit}";
}

输出为：鸡:7,兔:3