题目:从上往下打印出二叉树的每个节点,同层节点从左至右打印。
https://www.nowcoder.com/practice/7fe2212963db4790b57431d9ed259701
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
/**
public class TreeNode {
int val = 0;
TreeNode left = null;
TreeNode right = null;
public TreeNode(int val) {
this.val = val;
}
}
*/
public class Solution {
public ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {
ArrayList<Integer> result = new ArrayList<>();
if(root==null) return result;
Queue<TreeNode> queue = new LinkedList<>();
queue.add(root);
while(!queue.isEmpty()){
TreeNode node = queue.poll();
result.add(node.val);
if(node.left!=null) queue.add(node.left);
if(node.right!=null) queue.add(node.right);
}
return result;
}
}
网友评论