剑指offer60-把二叉树打印成多行-Java

题目描述

从上到下按层打印二叉树，同一层结点从左至右输出。每一层输出一行。

import java.util.ArrayList;
import java.util.Queue;
import java.util.LinkedList;
public class Solution {
    public ArrayList<ArrayList<Integer>> Print(TreeNode pRoot) {
        ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
        if(pRoot == null) return result;
        Queue<TreeNode> queue = new LinkedList<TreeNode>();
        queue.offer(pRoot);
        while(!queue.isEmpty()){
            int size = queue.size();
            ArrayList<Integer> rol = new ArrayList<Integer>();
            for(int i = 0;i < size;i++){
                TreeNode temp = queue.poll();
                rol.add(temp.val);
                if(temp.left != null) queue.offer(temp.left);
                if(temp.right != null) queue.offer(temp.right);
            }
            result.add(rol);
        }
        return result;
    }
}