合并 PHP 数组中的重叠范围? [英] Merging overlapping ranges in PHP arrays?

问题描述

我有一个以下格式的数组:

I have an array in the following format:

array(
  0 => array(1, 5),
  1 => array(4, 8),
  2 => array(19, 24),
  3 => array(6, 9),
  4 => array(11, 17),
);

其中每个项目都是 X 到 Y 的范围.我想合并数组中的重叠范围，以获得更像这样的内容:

Where each item is a X-to-Y range. What I would like to merge the overlapping ranges in the array, to get something more like this:

array(
  0 => array(1, 9), // 1-5, 4-8 and 6-9 are overlapping, so they are merged
  1 => array(11, 17),
  2 => array(19, 24),
);

实现这一目标的最佳方法是什么?

What would be the best way to accomplish this?

推荐答案

未测试，但这里的想法是先按第一个元素对数据进行排序，然后尽可能将后续元素与前一个元素合并.

Untested, but the idea here is to sort the data first by the first element, then merge subsequent elements with the previous one as long as possible.

usort($data, function($a, $b)
{
        return $a[0] - $b[0];
});

$n = 0; $len = count($data);
for ($i = 1; $i < $len; ++$i)
{
        if ($data[$i][0] > $data[$n][1] + 1)
                $n = $i;
        else
        {
                if ($data[$n][1] < $data[$i][1])
                        $data[$n][1] = $data[$i][1];
                unset($data[$i]);
        }
}

$data = array_values($data);

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