public static boolean isSameTree(TreeNode p, TreeNode q) {
		if (p == q && p == null) {
			return true;
		}
		if (p == null || q == null) {
			return false;
		}
		if (p.val == q.val) {
			boolean left = isSameTree(p.left, q.left);
			if (!left) {
				return false;
			}
			boolean right = isSameTree(p.right, q.right);

			if (!right) {
				return false;
			}
			return true;
		}
		return false;
	}