php数据结构之简单选择排序

<?php
1.     $array = array(13,15,6,10,20,6,3,19);
2.     $count = count($array);
3.     $n = $e = 0;
4.     for($i = 1; $i < $count; $i++)
5.     {
6.         //find the min item from $i to last
7.         $min_index = $i;
8.         for($j = $i+1; $j < $count; $j++)
9.         {
10.             $n++;
11.             if($array[$j] < $array[$min_index]) $min_index = $j;
12.         }
13.       
14.         if($array[$min_index] < $array[$i-1])
15.         {
16.             $e++;
17.         $tmp = $array[$i-1];
18.         $array[$i-1] = $array[$min_index];
19.         $array[$min_index] = $tmp;
20.         }
21.     }
22.     print_r($array);
23.     echo "共循环{$n}次，共执行{$e}次数据交换";
24. ?>

执行结果为：

Array ( [0] => 3 [1] => 6 [2] => 6 [3] => 10 [4] => 13 [5] => 15 [6] => 19 [7] => 20 )
1. 共循环21次，共执行5次数据交换