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;
}
}