PHP实现二分查找

function binary(&$arr,$low,$top,$target){
while($low <= $top){
$mid = floor(($low+$top)/2);
echo $mid."<br>";
if($arr[$mid]==$target){
return $arr[$mid];
}elseif($arr[$mid]<$target){
$low = $mid+1;
}else{
$top = $mid-1;
}
}
return -1;
}

function binaryRecursive(&$arr,$low,$top,$target){
if($low<=$top){
$mid = floor(($low+$top)/2);
if($mid==$target){
return $arr[$mid];
}elseif($arr[$mid]<$target){
return binaryRecursive($arr,$mid+1,$top,$target);
}else{
return binaryRecursive($arr,$low,$top-1,$target);
}
}else{
return -1;
}
}