NO.108 convert into an ordered array of binary search trees

An ordered array in accordance with the ascending order, is converted to a highly balanced binary search tree.

In this problem, a highly balanced binary tree is a binary tree refers to the left and right sub-tree of each node is the height difference between the absolute value of not more than 1.

Example:

Given an ordered array: [-10, -3,0,5,9],

One possible answer is: [0, -3,9, -10, null, 5], it can be expressed below this height balanced binary search tree:

      0
     / \
   -3   9
   /   /
 -10  5

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */

struct TreeNode*DFS(int* nums, int numsSize)
{
    if(numsSize<=0)return NULL;
    struct TreeNode*ret=(struct TreeNode*)malloc(sizeof(struct TreeNode));
    if(numsSize==1)
    {
        ret->val=nums[0];
        ret->left=NULL;
        ret->right=NULL;
    }
    else
    {
        int pos=(numsSize)/2;
        ret->val=nums[pos];
        ret->left=DFS(nums,pos);
        ret->right=DFS(nums+pos+1,numsSize-pos-1);
    }
    return ret;
}

struct TreeNode* sortedArrayToBST(int* nums, int numsSize){
    return DFS(nums,numsSize);
}

When execution: 12 ms, beat the 99.04% of all users in C submission

Memory consumption: 19.1 MB, defeated 100.00% of all users in C submission