2026/05/21

[LeetCode] 199 Binary Tree Right Side View

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/**
 * 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 {
private:
  std::vector<int> ans;
  void dfs(TreeNode *node, int depth) {
    if (!node)
      return;
    if (ans.size() < depth)
      ans.push_back(node->val);
    dfs(node->right, depth + 1);
    dfs(node->left, depth + 1);
  }

public:
  std::vector<int> rightSideView(TreeNode *root) {
    dfs(root, 1);
    return ans;
  }
};