[LeetCode 199] Binary Tree Right Side View (递归的层数）

2019-11-10 19:04:56

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题目内容

199 Binary Tree Right Side View 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].

Credits: Special thanks to @amrsaqr for adding this PRoblem and creating all test cases. 题目原文

题目简述

从上到下写出二叉树每层最右侧节点对应的数值

题目分析

按层次递归，并将层数作为递归变量使每层只记录一个数值，从右至左遍历则使每层右边节点最先遍历，该节点数值即可在本层唯一记录。

代码示例

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: void recursion(vector<int> &res,TreeNode *root,int level) { if(root==NULL) return; if(res.size()<level) res.push_back(root->val); recursion(res,root->right,level+1); recursion(res,root->left,level+1); } vector<int> rightSideView(TreeNode *root) { vector<int> res; recursion(res,root,1); return res; }};

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