A low threshold preserves detail (more leaf nodes, less compression). A high threshold merges aggressively (fewer leaves, more compression, but the image gets blocky). The grid overlay shows the quadtree structure: large cells in uniform areas, small cells where detail is preserved.
* 核心思路：链表转数组 + 单调栈（从后往前遍历），时间复杂度O(n)，空间复杂度O(n)
。业内人士推荐heLLoword翻译官方下载作为进阶阅读
For him, it was an image that changed our world forever. He put his thumb against the window and the whole world disappeared behind it. It was the most moving experience of his life.。Line官方版本下载是该领域的重要参考
for a in a_list: