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Binary Tree Right Side View

时间:2015-04-12 11:48:52      阅读:100      评论:0      收藏:0      [点我收藏+]

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Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

For example:
Given the following binary tree,

   1            <---
 /   2     3         <---
 \       5     4       <---

 

You should return [1, 3, 4].

 

层序遍历二叉树,依次输出每层最右节点即可,代码如下:

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public List<Integer> rightSideView(TreeNode root) {
        List<Integer> re_list = new ArrayList<Integer>();
        List<TreeNode> level_list = new ArrayList<TreeNode>();//层序遍历时存储当前层节点的list
        if(root==null) return re_list;
        level_list.add(root);
        re_list.add(root.val);
        int flag = 1;
        while(flag==1) {
            flag = 0;
            List<TreeNode> tmp_list = new ArrayList<TreeNode>();//用来存储下一层节点的list
            for(TreeNode node:level_list) {
                if(node.left!=null) {
                    flag = 1;//说明下层还存在节点
                    tmp_list.add(node.left);
                }
                if(node.right!=null) {
                    flag = 1;//说明下层还存在节点
                    tmp_list.add(node.right);
                }
            }
            int size = tmp_list.size();
            if(tmp_list.size()!=0) {
                re_list.add(tmp_list.get(size-1).val);//记录当前层最右边节点
                level_list.clear();
                level_list.addAll(tmp_list);//迭代
            }
        }
        return re_list;
    }
}

 

Binary Tree Right Side View

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原文地址:http://www.cnblogs.com/mrpod2g/p/4419130.html

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