给定一棵二叉树,采用广度优先搜索 BFS 返回其右视图,其中右视图中的每个节点都是该层最右侧的节 点。横线处应填写( )。

vector<int> rightSideView(TreeNode* root) {
    vector<int> result;
    if (!root) return result;
    queue<TreeNode*> q;
    q.push(root);
    while (!q.empty()) {
        int sz = q.size();
        for (int i = 0; i < sz; ++i) {
            TreeNode* node = q.front();
            q.pop();
            __________________________
            if (node->left) q.push(node->left);
            if (node->right) q.push(node->right);
        }
    }
    return result;
}

{{ select(1) }}

• if (i == 0) result.push_back(node->val);
• if (i == sz - 1) result.push_back(node->val);
• result.push_back(q.front()->val);
• if (node->right) result.push_back(node->right->val);