## Binary Tree Right Side View

07/16/2016 Tree Depth First Search Breadth First Search

## Question

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].

## Solution

Result: Accepted Time: 4 ms

Here should be some explanations.

/**
* 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 dfs(int depth,TreeNode * root,vector<int> &vec)
{
if(root == NULL) return;
if(vec.size() <=  depth)
vec.push_back(root->val);
dfs(depth+1,root->right,vec);
dfs(depth+1,root->left,vec);
}
vector<int> rightSideView(TreeNode* root) {
vector<int> vec;
dfs(0,root,vec);
return vec;
}
};

Complexity Analytics

• Time Complexity: $O(n)$
• Space Complexity: $O(1)$