<?php

//归并排序

function merge_sort($arr)

{

$len = count($arr);

if ($len <= 1){

return $arr;

}

$mid = intval($len / 2);

$left = array_slice($arr, 0, $mid);

$right = array_slice($arr, $mid);

$left = merge_sort($left);

$right = merge_sort($right);

return merge_arr($left, $right);

}

function merge_arr($left, $right)

{

$result = [];

while (count($left) && count($right)){

$result[] = $left[0] <= $right[0] ? array_shift($left) : array_shift($right);

}

return array_merge($result, $left, $right);

}

$arr = range(1,300000);

shuffle($arr);

echo "before sort:",implode(',', $arr),"\n";

$startTime = microtime(1);

$arr = merge_sort($arr);

$endTime = microtime(1);

echo "after sort:",implode(',', $arr),"\n";

echo "用时：".round($endTime - $startTime, 3),"\n";;

echo "内存：".memory_get_usage() / (1024*1024);