算法小能手
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。
import java.util.ArrayList;
import java.util.LinkedList;
public class Solution {
public ArrayList<Integer> PrintFromTopToBottom(TreeNode root) {
ArrayList<Integer> layerList = new ArrayList<Integer>();
if (root == null)
return layerList;
LinkedList<TreeNode> queue = new LinkedList<TreeNode>();
queue.add(root);
while (!queue.isEmpty()) {
TreeNode node = queue.poll();
layerList.add(node.val);
if (node.left != null)
queue.addLast(node.left);
if (node.right != null)
queue.addLast(node.right);
}
return layerList;
}
}