php二分查找的两种实现方法

function  binarySearch($arr, $val, $st, $et){
$m_ind = $st + floor(($et-$st)/2);
$max_idx = count($arr)-1;
$min_idx = 0;

if($arr[$min_idx]>$val || $arr[$max_idx]<$val || ($et-$st==1 && $arr[$et]!=$val && $arr[$st]!=$val)){
return -1;
}

if($arr[$m_ind]==$val){
return $m_ind;
} else if($arr[$m_ind] > $val){
$et = $m_ind - 1;
return binarySearch($arr, $val, $st, $et);
} else {
$st = $m_ind + 1;
return binarySearch($arr, $val, $st, $et);
}
}

function binarySearch($arr, $val){
$st = 0;
$et = count($arr) - 1;
$m_ind = floor(($et-$st)/2);
do{

if($arr[$m_ind]==$val){
return $m_ind;
} else if($arr[$m_ind] > $val){
$et = $m_ind - 1;
$off = ceil(($m_ind-$st)/2);
if($off == 0) return -1;
$m_ind = $m_ind - $off;
} else {
$st = $m_ind + 1;
$off = ceil(($et-$m_ind)/2);
if($off == 0) return -1;
$m_ind = $m_ind + $off;
}
}while(true);
}