LeetCode-Algorithms-[Easy][树]面试题28. 对称的二叉树

面试题28. 对称的二叉树

	public boolean isSymmetric(TreeNode root) {
		if (root == null) {
			return true;
		}
		return isSym(root.left, root.right);
	}

	private boolean isSym(TreeNode leftNode, TreeNode rightNode) {
		if (leftNode == null && rightNode == null) {
			return true;
		}
		if (leftNode == null || rightNode == null || leftNode.val != rightNode.val) {
			return false;
		}
		return isSym(leftNode.left, rightNode.right) && isSym(leftNode.right, rightNode.left);
	}