PHP实现二分法查找

二分查找法需要数组是一个有序的数组。

<?php
function binarySearch($num, $arr) {
	$start = 0;
	$end = count($arr);
	$mid = floor(($start+$end)/2);

	while ($start<$end-1) {
		if ($num == $arr[$mid]) {
			return $mid;
		} elseif ($num < $arr[$mid]) {
			$end = $mid;
			$mid = floor(($start+$end)/2);
		} else {
			$start = $mid;
			$mid = floor(($start+$end)/2);
		}
	}
	return false;
}
$arr = [1,2,3,4,5,6,7,8,9,10];
$result = binarySearch(7,$arr);
print_r($result);