题解 | #判断二叉树是否对称#

public boolean isSymmetric (TreeNode root) {
// write code here
if(root == null) return true;
Queue<treenode> queue=new LinkedList<treenode>();
queue.offer(root.left);
queue.offer(root.right);
while(!queue.isEmpty()){
TreeNode left=queue.poll();
TreeNode right=queue.poll();
if(left ==null && right ==null){//继续比较
continue;
}
if(left ==null || right ==null || left.val != right.val){
return false;
}
queue.offer(left.left);//加入左字节点的左节点
queue.offer(right.right);
queue.offer(left.right);
queue.offer(right.left);
}
return true;
}</treenode></treenode>