# 543.Diameter-of-Binary-Tree

## 题目地址

https://leetcode.com/problems/diameter-of-binary-tree/

## 题目描述

``````Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.

Example:
Given a binary tree
1
/ \
2   3
/ \
4   5
Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].

Note: The length of path between two nodes is represented by the number of edges between them.``````

## 代码

### Approach 1: DFS

``````/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }
*/
class Solution {
int ans = 0;
public int diameterOfBinaryTree(TreeNode root) {
dfs(root)
return ans;
}

public int dfs(TreeNode node) {
if (node == null)    return 0;

int L = dfs(node.left);
int R = dfs(node.right);
ans = Math.max(ans, L + R);

return Math.max(L, R) + 1;
}
}``````

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