/**
 * 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* solve(vector<int>&nums, int i, int j){
        if(i>j) return NULL;
        int mid = (i+j)/2;
        auto root = new TreeNode(nums[mid]);
        root->left = solve(nums, i, mid-1);
        root->right = solve(nums, mid+1, j);
        return root;
    }
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        return solve(nums, 0, nums.size()-1);
    }
    
};