LeetCode/199.cpp at main · vys1n/LeetCode · GitHub

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#include <bits/stdc++.h>
#include <queue>
#include <vector>
using namespace std;

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> res;
        queue<TreeNode*> q;
        q.push(root);

        while (!q.empty()) {
            int sz = q.size();

            for (int i=0; i<sz; i++) {
                TreeNode* cur = q.front();
                q.pop();

                if (i == sz-1)
                    res.push_back(cur->val);
                if (cur->left)
                    q.push(cur->left);
                if (cur->right)
                    q.push(cur->right);
            }
        }

        return res;
    }
};