[LeetCode] Binary Tree Right Side View, leetcodebinary

[LeetCode] Binary Tree Right Side View, leetcodebinary

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 shoshould return[1, 3, 4].

Solution: This question is relatively simple and can be done in a way similar to sequential traversal, but it is a bit different. The traversal order is root, right, and left. Use a map to record the first value of each layer. The following code is used:

/*** Definition for binary tree * struct TreeNode {* int val; * TreeNode * left; * TreeNode * right; * TreeNode (int x): val (x ), left (NULL), right (NULL) {}*}; */class Solution {public: vector <int> rightSideView (TreeNode * root) {map <int, int> levelToVal; // record the first occurrence value of each layer. Tranver (root, 0, levelToVal); vector <int> result; for (map <int, int>: iterator it = levelToVal. begin (); it! = LevelToVal. end (); it ++) {result. push_back (it-> second);} return result;} // similar to first-order traversal, however, the order is top, right, left void tranver (TreeNode * node, int level, map <int, int> & levelToVal) {if (node = NULL) {return;} map <int, int>: iterator it = levelToVal. find (level); if (it = levelToVal. end () {levelToVal. insert (map <int, int >:: value_type (level, node-> val);} tranver (node-> right, level + 1, levelToVal ); tranver (node-> left, level + 1, levelToVal );}};