剑指offer--把二叉树打印成多行

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;


/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
	ArrayList<ArrayList<Integer> > Print(TreeNode pRoot) {
		ArrayList<ArrayList<Integer>> result = new ArrayList<ArrayList<Integer>>();
		if(pRoot==null) return result;
		ArrayList<TreeNode> queue = new ArrayList<TreeNode>();
		ArrayList<Integer> temp = new ArrayList<Integer>();
		ArrayList<Integer> start = new ArrayList<Integer>();
		start.add(pRoot.val);
		result.add(start);
		int low = 0;
		int high = 1;
		int end = high;	
		queue.add(pRoot);
		while(low<high){			
			TreeNode t = queue.get(low);
			if(t.left!=null){
				queue.add(t.left);
				temp.add(t.left.val);
				high++;
			}
			if(t.right!=null){
				queue.add(t.right);
				temp.add(t.right.val);
				high++;
			}
			low++;
			if(low==end){
				end = high;
				if(temp.size()!=0)
					result.add(temp);
				temp = new ArrayList<Integer>();
			}
		}
		return result;
	}
	
}