[LeetCode]Convert Sorted Array to Binary Search Tree

[cpp] 
struct TreeNode { 
    int val; 
    TreeNode *left; 
    TreeNode *right; 
    TreeNode(int x) : val(x), left(NULL), right(NULL) {} 
}; 
 
class Solution { 
public: 
    TreeNode* Convert2BST(vector<int>& num, int start, int end) 
    { 
        if(start > end) 
            return NULL; 
        int mid = (start+end)/2; 
        TreeNode* pNode = new TreeNode(num[mid]); 
        pNode->left = Convert2BST(num, start, mid-1); 
        pNode->right = Convert2BST(num, mid+1, end); 
        return pNode; 
    } 
    TreeNode *sortedArrayToBST(vector<int> &num) { 
        // Start typing your C/C++ solution below  
        // DO NOT write int main() function  
        return Convert2BST(num, 0, num.size()-1); 
    } 
}; 

struct TreeNode {
 int val;
 TreeNode *left;
 TreeNode *right;
 TreeNode(int x) : val(x), left(NULL), right(NULL) {}
};

class Solution {
public:
 TreeNode* Convert2BST(vector<int>& num, int start, int end)
 {
  if(start > end)
   return NULL;
  int mid = (start+end)/2;
  TreeNode* pNode = new TreeNode(num[mid]);
  pNode->left = Convert2BST(num, start, mid-1);
  pNode->right = Convert2BST(num, mid+1, end);
  return pNode;
 }
    TreeNode *sortedArrayToBST(vector<int> &num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        return Convert2BST(num, 0, num.size()-1);
    }
};