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; } }