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:
  • Space Complexity: