PHP rearranges a set of numbers (bubble algorithm)

How to reorder the known array $arr = [24,69,80,57,13].

Idea:

1. We need to compare each two in the array before and after. If the front is smaller than the back, exchange the position;

2. Because it is Two-to-one comparison, so we need to compare count($arr) - 1 round, because after each round of comparison, a maximum value can be determined, so each round will be reduced once.

Illustration:

Code:

//定义数组
$arr = [24,69,80,57,13];
//定义一个临时变量
$temp = 0;
//第一层循环，外层循环，循环count($arr) - 1 次(可以遍历到每一个数组值)
for ($i1=0; $i1 < count($arr); $i1++) { 
    //第二层循环，内层循环，每一次外层循环内，再次循环，循环次数依次减少一次(每次循环结束，可以获取到一个最大值)
    for ($i=0; $i < count($arr) - 1; $i++) {
        //判断条件，满足即交换值 
        if($arr[$i] > $arr[$i + 1]){
            //临时存储满足条件的变量值
            $temp = $arr[$i];
            //重新赋值
            $arr[$i] = $arr[$i + 1];
            //重新赋值
            $arr[$i + 1] = $temp;
        }
    }
}
//输出排列后的数组
echo &#39;<pre class="brush:php;toolbar:false">&#39;;
var_dump($arr);

The final result is:

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