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程式語言 - LeetCode - C++ - 655. Print Binary Tree

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題目：


解答：

/**
 * 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<vector<string>> printTree(TreeNode* root) {
        auto high = [](this auto&& depth, TreeNode *n) -> int {
            if (!n) {
                return 0;
            }

            int l = depth(n->left);
            int r = depth(n->right);

            return max(l, r) + 1;
        };

        int h = high(root);
        int w = (1 << h) - 1;
        vector<vector<string>> ans(h, vector<string>(w, ""));

        auto dfs = [&](this auto&& dfs, TreeNode *n, int row, int l, int r) -> void {
            if (!n) {
                return;
            }

            int m = (l + r) >> 1;
            ans[row][m] = to_string(n->val);
            dfs(n->left, row + 1, l, m - 1);
            dfs(n->right, row + 1, m + 1, r);
        };
        
        dfs(root, 0, 0, w - 1);

        return ans;
    }
};