22.java

import java.util.ArrayList;
import java.util.Queue;
import java.util.LinkedList;
/**
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<Integer>();
        if(root==null) return result;
        Queue<TreeNode> queue=new LinkedList<TreeNode>();
        queue.offer(root);
        
        while(!queue.isEmpty())
        {
            TreeNode temp=queue.poll();
            if(temp.left!=null)
                queue.offer(temp.left);
            if(temp.right!=null)
                queue.offer(temp.right);
           result.add(temp.val);
        }
        return result;
    }
}