199.binary-tree-right-side-view.cpp

/*
 * @lc app=leetcode id=199 lang=cpp
 *
 * [199] Binary Tree Right Side View
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<int> rightSideView(TreeNode* root) {
        if(!root)
            return {};
        vector<int> ans;
        if(!root) return ans;
        queue<TreeNode *> q;
        q.push(root);
        while (!q.empty())
        {
            vector<int> vtr;
            int size=q.size();
            for (int i = 0; i < size; i++)
            {
                TreeNode* curr=q.front();
                q.pop();
                if(curr->left){
                    q.push(curr->left);
                }
                if(curr->right){
                    q.push(curr->right);
                }
                vtr.push_back(curr->val);
            }
            ans.push_back(vtr[vtr.size()-1]);
        }
        return ans;
    }

};
// @lc code=end