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<?php

/**

* 快速查询

*

* @author Pu ShaoWei <pushaowei0727@gmail.com>

* @date 2017/8/23

* @license MIT

* -------------------------------------------------------------

* 思路分析：数组中间的值floor((low+top)/2) 

* -------------------------------------------------------------

* 重复第二步操作直至找出目标数字

*/

/**

* QuickQuery

*

* @param $array

* @param $k

* @param int $low

* @param int $high

* @return int

*/

function QuickQuery($array, $k, $low = 0, $high = 0)

{

//判断是否为第一次调用

if (count($array) != 0 and $high == 0) {

$high = count($array);

}

//如果还存在剩余的数组元素

if ($low <= $high) {

//取$low和$high的中间值

$mid = intval(($low + $high) / 2);

//如果找到则返回

if ($array[$mid] == $k) {

return $mid;

} else if ($k < $array[$mid]) {//如果没有找到，则继续查找

return QuickQuery($array, $k, $low, $mid - 1);

} else {

return QuickQuery($array, $k, $mid + 1, $high);

}

}

return -1;

}

echo QuickQuery([4, 5, 7, 8, 9, 10, 8], 8);