题目描述
示例
做题思路
知识点
代码
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public int[] levelOrder(TreeNode root) {
//空判断
if(root==null){
return new int[0];
}
Queue<TreeNode> queue=new LinkedList<>();
List<Integer> list=new ArrayList<>();
queue.offer(root);//将根添加进队列
while(!queue.isEmpty()){
TreeNode t=queue.poll();
list.add(t.val);
if(t.left!=null){
queue.offer(t.left);//将左节点添加进队列
}
if(t.right!=null){
queue.offer(t.right);//将右节点添加进队列
}
}
int len=list.size();
int[] result=new int[len];
for(int i=0;i<len;i++){
result[i]=list.get(i);
}
return result;
}
}