PHP 冒泡排序和二分查找示例

<?php
for ($i = 0; $i < $num - 1; $i++) {
    for ($m = 0; $m < $num - 1; $m++) {
        if ($arr[$m] < $arr[$m + 1]) {
            $temp = $arr[$m];
            $arr[$m] = $arr[$m + 1];
            $arr[$m + 1] = $temp;
        }
        // echo $arr[$m].&#39;<br>&#39;;
        
    }
}
//输出排序后的结果
var_dump($arr);
//冒泡顺序排列
for ($x = 0; $x < $num - 1; $x++) {
    for ($y = 0; $y < $num - 1; $y++) {
        if ($arr[$y] > $arr[$y + 1]) {
            $temp = $arr[$y];
            $arr[$y] = $arr[$y + 1];
            $arr[$y + 1] = $temp;
        }
    }
}
//输出排序后的结果
var_dump($arr);
//二分法查找
function dichotomy($array, $k, $low = 0, $high = 0) {
    if (count($array) != 0 && $high == 0) {
        $high = count($array);
    }
    if ($low <= $high) {
        $mid = intval(($low + $high) / 2);
        if ($array[$mid] == $k) {
            return $mid;
        } elseif ($k < $array[$mid]) {
            return dichotomy($array, $k, $low = 0, $mid - 1);
        } else {
            return dichotomy($array, $k, $mid + 1, $high);
        }
    } else {
        return false;
    }
}
//输出查找结果
echo dichotomy($arr, 23);
?>