* Definition for a binary tree node.
* public class TreeNode {
* TreeNode(int x) { val = x; }
public int diameterOfBinaryTree(TreeNode root) {
int[] diameter = new int[1];
getDiameterOfTree(root, diameter);
public int getDiameterOfTree(TreeNode node, int[] diameter) {
int leftDiameter = getDiameterOfTree(node.left, diameter);
int rightDiameter = getDiameterOfTree(node.right, diameter);
diameter[0] = Math.max(diameter[0], leftDiameter + rightDiameter);
return 1 + Math.max(leftDiameter, rightDiameter);