C++

/** * Definition of TreeNode: * class TreeNode { * public: *     int val; *     TreeNode *left, *right; *     TreeNode(int val) { *         this->val = val; *         this->left = this->right = NULL; *     } * } */class Solution {public:    /**     * @param A: A sorted (increasing order) array     * @return: A tree node     */    TreeNode *sortedArrayToBST(vector
     
       &A) {        // write your code here        if (0 == A.size()) {            return NULL;        }        return buildTree(A, 0, A.size()-1);    }    TreeNode *buildTree(vector
      
        &A, int from, int to) {        if (from > to) {            return NULL;        }        int mid = (from+to)/2;        TreeNode *node = new TreeNode(A[mid]);        node->left = buildTree(A, from, mid-1);        node->right = buildTree(A, mid+1, to);        return node;    }};