| 227 | } |
| 228 | |
| 229 | public boolean isSymmetric(TreeNode root) { |
| 230 | Queue<TreeNode> queue = new LinkedList<>(); |
| 231 | queue.add(root.left); |
| 232 | queue.add(root.right); |
| 233 | |
| 234 | while(!queue.isEmpty()) { |
| 235 | TreeNode left = queue.poll(); |
| 236 | TreeNode right = queue.poll(); |
| 237 | |
| 238 | if(left == null && right == null) { |
| 239 | continue; |
| 240 | } |
| 241 | |
| 242 | if(left == null || right == null) { |
| 243 | return false;; |
| 244 | } |
| 245 | |
| 246 | if (left.val != right.val) { |
| 247 | return false; |
| 248 | } |
| 249 | |
| 250 | queue.add(left.left); |
| 251 | queue.add(right.right); |
| 252 | queue.add(left.right); |
| 253 | queue.add(right.left); |
| 254 | |
| 255 | } |
| 256 | return true; |
| 257 | } |
| 258 | |
| 259 | |
| 260 | |