二分查找法

<?php//$k为要查找的关键字（注：待查找的数组元素为奇数个）function bin_sch($array, $low, $high, $k){     if ($low <= $high)    {         $mid = intval(($low+$high)/2);         if ($array[$mid] == $k)        {             return true;         }        elseif ($k < $array[$mid])        {             return bin_sch($array, $low, $mid-1, $k);         }        else        {             return bin_sch($array, $mid+1, $high, $k);         }     }     return false; } $array = array(1, 2, 4, 6, 8, 20, 22);$k = 20;if(bin_sch($array, min(array_keys($array)), max(array_keys($array)), $k)){echo "二分查找成功";}else{echo "二分查找失败";}?>