Solution.cpp

/**
 * 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:
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        function<TreeNode*(int, int)> dfs = [&](int l, int r) -> TreeNode* {
            if (l > r) {
                return nullptr;
            }
            int mid = (l + r) >> 1;
            auto left = dfs(l, mid - 1);
            auto right = dfs(mid + 1, r);
            return new TreeNode(nums[mid], left, right);
        };
        return dfs(0, nums.size() - 1);
    }
};