Solution 11: 二叉树中节点的最大距离

public class MaxDistanceInTree {
	public int getMaxDistanceInTree(TreeNode root) {
		if (root == null) {
			return 0;
		}

		int leftHeight = getHeightOfTree(root.left);
		int rightHeight = getHeightOfTree(root.right);

		return leftHeight + rightHeight;
	}

	private int getHeightOfTree(TreeNode root) {
		if (root == null) {
			return 0;
		}

		return Math
				.max(getHeightOfTree(root.left), getHeightOfTree(root.right)) + 1;
	}
}