Day35: [LeetCode简单] 108. 将有序数组转换为二叉搜索树

题源：

来自leetcode题库：

https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree/

代码：

dirty code凑合看吧

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int Len;
    TreeNode* f(vector<int>& nums,int left,int right){
        if(left>right) return NULL;
        int mid=(left+right)/2;
        TreeNode* p=new TreeNode(nums[mid]);
        p->left=f(nums,left,mid-1);
        p->right=f(nums,mid+1,right);
        return p;
    }
    TreeNode* sortedArrayToBST(vector<int>& nums) {

        Len=nums.size();
        if(Len==0) return NULL;
        return f(nums,0,Len-1);
    }
};