PHP 實現二分查詢

PHP迴圈實現二分查詢

function search($search, $arr)
{
    $start = 0;
    $length = count($arr);
    while($start < $length - 1 && in_array($search,$arr))
    {
        $mid =  floor(($start+$length)/2);
        if($arr[$mid] == $search){
            return $mid;
        } else if ($arr[$mid] < $search){
            $start = $mid + 1;
        } else if ($arr[$mid] > $search){
            $length = $mid - 1;
        }
    }
    return false;
}

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