php - Simple string processing, looking for ideas.

Question

$arr = [2,3,4,5,8,10,11,12,13,16,19];

Convert to string

2-5, 8, 10-13, 16, 19

My personal idea is to select 8 16 19 that do not rely on both sides, and then select a maximum and minimum value from 2 3 4 5.

Answer 1

Note down the starting point value and scan backward. If it is continuous, continue backward. Otherwise, note down the end point value and get a beg-end or beg. continue...

Answer 2

$arr=array(2,3,4,5,8,10,11,12,13,16,19);
//最大值
$max=max($arr);
//求和
$sun=array_sum($arr);
//排序
asort($arr);
//a1为标准数组，用来判断值是否存在
//a2用来存放已经被使用过的数
//a3为最后的结果数组
foreach ($arr as $key => $value) {
    
     $a1[$value]=$value;
}

foreach ($arr as $key => $value) {
     if(!isset($a2[$value])){
             $start=$value;
             $end=$value;
        
             $a2[$value]=$value;
             for($i=0;$i<$sun;$i++){
            
                            $end = $end+1;
                            if(isset($a1["$end"])){
                
                                $a2[$end]=$end;
            
                            }else{
                                $end =$end-1;
                                if($start==$end){
                                  $a3 []= $start;
                                }else{
                                  $a3 []=   $start."-".$end;
                                }
                                
                               //断开了，跳出循环
                                break;
                            }
            
            
               }
       }
}

echo '<pre>';
var_dump($a3);

die;

Answer 3

Split the array into 5 pieces, and then process the sub-arrays.