import java.util.*;
/*
- public class TreeNode {
- int val = 0;
- TreeNode left = null;
- TreeNode right = null;
- public TreeNode(int val) {
-
this.val = val;
- }
- } */
public class Solution { int res=0; public int diameterOfBinaryTree (TreeNode root) { dfs(root); return res; } public int dfs(TreeNode root){ if(root==null) return 0; int left=dfs(root.left); int right=dfs(root.right); res=Math.max(res,left+right); return Math.max(left,right)+1; } }