![\"\"](\"https://assets.leetcode.com/uploads/2020/10/13/ex1.jpg\")
Given the root of a binary tree, return the length of the longest path, where each node in the path has the same value. This path may or may not pass through the root.
The length of the path between two nodes is represented by the number of edges between them.
\n\n\n
Example 1:
\n\n\nInput: root = [5,4,5,1,1,null,5]\nOutput: 2\nExplanation: The shown image shows that the longest path of the same value (i.e. 5).\n\n\n
Example 2:
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/10/13/ex2.jpg\")
\n\nInput: root = [1,4,5,4,4,null,5]\nOutput: 2\nExplanation: The shown image shows that the longest path of the same value (i.e. 4).\n\n\n
\n
Constraints:
\n\n[0, 104].-1000 <= Node.val <= 10001000.给定一个二叉树的 root ，返回 最长的路径的长度 ，这个路径中的 每个节点具有相同值 。 这条路径可以经过也可以不经过根节点。
两个节点之间的路径长度 由它们之间的边数表示。
\n\n\n\n
示例 1:
\n\n
\n输入：root = [5,4,5,1,1,5]\n输出：2\n\n\n
示例 2:
\n\n
\n输入：root = [1,4,5,4,4,5]\n输出：2\n\n\n
\n\n
提示:
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collections<\\/a>\\u3002\\u5982\\u679c\\u60a8\\u9700\\u8981\\u4f7f\\u7528\\u5176\\u4ed6\\u5e93\\u51fd\\u6570\\uff0c\\u8bf7\\u81ea\\u884c\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u6ce8\\u610f Python 2.7 \\u5c06\\u57282020\\u5e74\\u540e\\u4e0d\\u518d\\u7ef4\\u62a4<\\/a>\\u3002 \\u5982\\u60f3\\u4f7f\\u7528\\u6700\\u65b0\\u7248\\u7684Python\\uff0c\\u8bf7\\u9009\\u62e9Python 3\\u3002<\\/p>\"],\"c\":[\"C\",\" \\u7248\\u672c\\uff1a \\u7f16\\u8bd1\\u65f6\\uff0c\\u5c06\\u4f1a\\u91c7\\u7528 \\u4e3a\\u4e86\\u4f7f\\u7528\\u65b9\\u4fbf\\uff0c\\u5927\\u90e8\\u5206\\u6807\\u51c6\\u5e93\\u7684\\u5934\\u6587\\u4ef6\\u5df2\\u7ecf\\u88ab\\u81ea\\u52a8\\u5bfc\\u5165\\u3002<\\/p>\\r\\n\\r\\n \\u5982\\u60f3\\u4f7f\\u7528\\u54c8\\u5e0c\\u8868\\u8fd0\\u7b97, \\u60a8\\u53ef\\u4ee5\\u4f7f\\u7528 uthash<\\/a>\\u3002 \\\"uthash.h\\\"\\u5df2\\u7ecf\\u9ed8\\u8ba4\\u88ab\\u5bfc\\u5165\\u3002\\u8bf7\\u770b\\u5982\\u4e0b\\u793a\\u4f8b:<\\/p>\\r\\n\\r\\n 1. 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