php 实现二分查找

<?phpfunction binSearch($arr,$low,$high,$k){if($low<=$high){$mid = intval(($low+$high)/2);if($arr[$mid] == $k){return $mid;}elseif($k<$arr[$mid]){return binSearch($arr,$low,$mid-1,$k);}else{return binSearch($arr,$mid+1,$high,$k);}}return -1;}$arr = array(9,1,3,4,5);echo binSearch($arr,0,count($arr),4);?>