A quadtree does the same thing for two-dimensional space. It takes a rectangular region and divides it into four equal quadrants: northwest, northeast, southwest, southeast. If a quadrant has too many points in it, it subdivides again and again. Each subdivision creates smaller and smaller cells where points are densely packed.
思路：① 找初始左边界：第一个 nums[i] nums[i+1]；② 找初始右边界：最后一个 nums[i] < nums[i-1]；③ 求 [left,right] 内 min、max；④ 向左扩展：nums[left-1] minVal 则 left--；⑤ 向右扩展：nums[right+1] < maxVal 则 right++。长度 = right - left + 1。
。关于这个话题，WPS官方版本下载提供了深入分析
Москвичи пожаловались на зловонную квартиру-свалку с телами животных и тараканами18:04
Photographer: Yuki Iwamura/Bloomberg
union object_info *to_be_deleted[num_classes] = {0};