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class Solution {
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 public:
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  vector<vector<string>> res;
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  int height(TreeNode *root) {
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    if (!root) return 0;
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    return 1 + max(height(root->left), height(root->right));
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  }
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  void fill(TreeNode *root, int r, int c, int h) {
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    if (!root) return;
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    res[r][c] = to_string(root->val);
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    fill(root->left, r + 1, c - pow(2, h - r - 1), h);
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    fill(root->right, r + 1, c + pow(2, h - r - 1), h);
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  }
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  vector<vector<string>> printTree(TreeNode *root) {
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    int h = height(root);
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    int c = pow(2, h) - 1;
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    res.resize(h, vector<string>(c, ""));
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    fill(root, 0, (c - 1) / 2, h - 1);
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    return res;
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  }
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};