public class Solution
extends Object
652 - Find Duplicate Subtrees\.
Medium
Given the `root` of a binary tree, return all **duplicate subtrees**.
For each kind of duplicate subtrees, you only need to return the root node of any **one** of them.
Two trees are **duplicate** if they have the **same structure** with the **same node values**.
**Example 1:**
**Input:** root = [1,2,3,4,null,2,4,null,null,4]
**Output:** [[2,4],[4]]
**Example 2:**
**Input:** root = [2,1,1]
**Output:** [[1]]
**Example 3:**
**Input:** root = [2,2,2,3,null,3,null]
**Output:** [[2,3],[3]]
**Constraints:**
* The number of the nodes in the tree will be in the range `[1, 10^4]`
* `-200 <= Node.val <= 200`