Diameter of Binary Tree

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public int diameterOfBinaryTree(TreeNode root) {
        if(root == null){
            return 0;
        }
        return diameter(root) - 1;
    }
    
    public static int diameter(TreeNode root){
        if(root == null){
            return 0;
        }
        
        int lheight = height(root.left);
        int rheight = height(root.right);
        
        int ldiameter = diameter(root.right);
        int rdiameter = diameter(root.left);
        
        return Math.max(lheight + rheight + 1, Math.max(ldiameter, rdiameter));
    }
    
    public static int height(TreeNode node){
        if(node == null){
            return 0;
        }
        
        return (1 + Math.max(height(node.left), height(node.right)));
    }
}