LeetCode（剑指 Offer）- 28. 对称的二叉树

/*** Definition for a binary tree node.* public class TreeNode {*     int val;*     TreeNode left;*     TreeNode right;*     TreeNode(int x) { val = x; }* }*/classSolution {
publicint[] levelOrder(TreeNoderoot) {
if(root==null) returnnewint[0];
Queue<TreeNode>queue=newLinkedList<>(){{ add(root); }};
ArrayList<Integer>ans=newArrayList<>();
while(!queue.isEmpty()) {
TreeNodenode=queue.poll();
ans.add(node.val);
if(node.left!=null) queue.add(node.left);
if(node.right!=null) queue.add(node.right);
        }
int[] res=newint[ans.size()];
for(inti=0; i<ans.size(); i++)
res[i] =ans.get(i);
returnres;
    }
}