1. 后序遍历标记每个节点的深度(从后至上) 2. 先序遍历 * * * * [https://leetcode.com/problems/height-of-binary-tree-after-subtree-removal-queries/](https://leetcode.com/problems/height-of-binary-tree-after-subtree-removal-queries/) * [https://leetcode.com/problems/height-of-binary-tree-after-subtree-removal-queries/discuss/2758211/Java-2-pass-DFS-with-HashMaps](https://leetcode.com/problems/height-of-binary-tree-after-subtree-removal-queries/discuss/2758211/Java-2-pass-DFS-with-HashMaps)
