import java.util.*;
public class Main {
/**
//该段代码仅用于调试,提交时请注释该段代码
class TreeNode<T> {
public T data;
public TreeNode<T> left;
public TreeNode<T> right;
}
*/
public int[] solution(TreeNode<Integer> root) {
if(root ==null){
return null;
}
List<Integer> list = new ArrayList<>();
Queue<TreeNode<Integer>> q = new LinkedList<>();
TreeNode<Integer>p=root;
q.add(p);
while (q.isEmpty() == false)
{
p=q.poll();
list.add(p.data);
if (p.left != null)
{
q.add(p.left);
}
if (p.right != null)
{
q.add(p.right);
}
}
int[] a = new int[list.size()];
for (int i = 0; i < a.length; i++) {
a[i] = list.get(i);
}
return a;
}
}