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力扣--LCR 149.彩灯装饰记录I

article 2025/2/7 14:25:37

题目

在这里插入图片描述

代码

/**

Definition for a binary tree node.
public class TreeNode {
```
int val;
```
```
TreeNode left;
```
```
TreeNode right;
```
```
TreeNode() {}
```
```
TreeNode(int val) { this.val = val; }
```

TreeNode(int val, TreeNode left, TreeNode right) {

```
    this.val = val;
```
```
    this.left = left;
```
```
    this.right = right;
```
```
}
```

}
*/
class Solution {
public int[] decorateRecord(TreeNode root) {
if(root == null){
return new int[0];
}

 Queue<TreeNode> queue = new LinkedList<>();
 List<Integer> res = new ArrayList<>();

 queue.add(root);
 while(!queue.isEmpty()){
     TreeNode t = queue.poll();
     res.add(t.val);
     if(t.left != null) queue.add(t.left);
     if(t.right != null) queue.add(t.right);
 }

 int[] arr = new int[res.size()];
 for(int i = 0; i < res.size(); i++){
     arr[i] = res.get(i);
 }

 return arr;

}
}
时间复杂度：O(n)
额外空间复杂度：容器里最对存放 1/2 的节点，故为 O(n)

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