PHP合并两个数组与范围

I have two arrays :

$a = array(
array("begin"=>0, "end"=>200,"value"=>90),
array("begin"=>200, "end"=>600,"value"=>50),
array("begin"=>600, "end"=>1000,"value"=>90)
);

$b = array(
array("begin"=>-5, "end"=>50,"value"=>10),
array("begin"=>550, "end"=>590,"value"=>30)
);

Target, merging two arrays with the following criteria:

1. merging the array $b into $a (called $result)
2. if item in $b overlap with any item in array $a, it should cut the interval in $a
3. for any two intervals with same "begin" & "end" after 2), it should choose the smaller value

The answer i would expected:

$result = array(
    array("begin"=>-5, "end"=>50,"value"=>10),
    array("begin"=>50, "end"=>200,"value"=>90),
    array("begin"=>200, "end"=>550,"value"=>50),
    array("begin"=>550, "end"=>590,"value"=>30),
    array("begin"=>590, "end"=>600,"value"=>50),
    array("begin"=>600, "end"=>1000,"value"=>90)
    );

What would be the best way to accomplish this? Thank you everyone.

Thanks everyone idea. I just come up with the code and post it here in case if someone have the same problem, they could make reference to.

I first combine the $a and $b to a single array $tmp_combine and sort them according to 'begin'. Construct an unique sorted index array $ind containing all 'start' and 'end' of the $tmp_combine. Then calculate the min value for each index point pair from $tmp_combine, construct an array $ind_SR.

for number of item in $ind_SR, do the merge if they have the same value consecutively and output the final answer to $result.

 $tmp_combine = array_orderby(array_merge($a,$b), 'begin', SORT_ASC);

       $ind = array_merge(array_column($tmp_combine, 'begin'),array_column($tmp_combine, 'end'));

       $ind =  array_unique($ind);
       asort($ind);
       $ind = array_values($ind);

       $index = 0;
       $ch_now = $ind[0];


      for ($i=0; $i<count($ind)-1; $i++){ //calculate the mid pt min value
         $mid_pt = ($ind[$i] + $ind[$i+1]) /2;
         array_push($ind_SR, find_min_SR($tmp_combine,$mid_pt));
        }

      for ($i=0; $i<count($ind_SR); $i++){

         if ($ch_now <= $ind[$i]){
         $start = $ind[$i];
         $end = $ind[$i+1];
         $result[$index]['begin'] = $ind[$i];

         for ($j=$i; $j<count($ind_SR); $j++){
            $start_j = $ind[$j];
            $end_j = $ind[$j+1];

            if ($ind_SR[$j] == $ind_SR[$i]){
                $result[$index]['begin'] = $start;
               $result[$index]['end']  = $end_j ;
               $result[$index]['value'] =  $ind_SR[$i];
                $ch_now = $ind[$j+1];
            } else{
                $result[$index]['end']  = $ind[$j] ;
                break; break;
            }

         }


        $index++;  

        }

Use array_merge() function

$result = array_merge($a,$b);

then use asort() function to sort array