php 二分查找

二分查找需要数组有序,效率为O(logn)

#二分查找functionbinarySearch(Array $arr, $target) {$low = 0;
        $high = count($arr) - 1;

        while($low $high) {
            $mid = floor(($low + $high) / 2);
            #找到元素if($arr[$mid] == $target) return$mid;
            #中元素比目标大,查找左部if($arr[$mid] > $target) $high = $mid - 1;
            #重元素比目标小,查找右部if($arr[$mid] $target) $low = $mid + 1;
        }

        #查找失败returnfalse;
    }

    $arr = array(1, 3, 5, 7, 9, 11);
    $inx = binarySearch($arr, 1);
    var_dump($inx);
?>