108. Convert Sorted Array to Binary Search Tree.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) {
        if(nums.size()==NULL)
        {
            return NULL;
        }
        return constructBSTRecursive(nums,0,nums.size()-1);
        
    }
    
    TreeNode* constructBSTRecursive(vector<int>& nums,int left,int right){
        if(left>right)
        {
            return NULL;
        }
        int mid = left+(right-left)/2;
        TreeNode* curr= new TreeNode(nums[mid]);
        curr->left = constructBSTRecursive(nums,left,mid-1);
        curr->right = constructBSTRecursive(nums,mid+1,right);
        return curr;
        
        
        
        
    }
};