Right view of binary tree by Recursion.

-

 class Solution

{

public:

    void treeHelper(TreeNode *root, map<int, int> &mp, int &mx_lvl, int cur_lvl)

    {

        if (root == NULL)

            return;

        if (mx_lvl < cur_lvl)

        {

            mx_lvl = cur_lvl;

            mp[mx_lvl] = root->val;

        }

        treeHelper(root->right, mp, mx_lvl, cur_lvl + 1);

        treeHelper(root->left, mp, mx_lvl, cur_lvl + 1);

    }

    vector<int> rightSideView(TreeNode *root)

    {

        map<int, int> ans;

        int mx_lvl = -1;

        treeHelper(root, ans, mx_lvl, 0);

        vector<int> final;

        for (auto it : ans)

            final.push_back(it.second);

        return final;

    }

};

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