LeetCode 108. 将有序数组转换为二叉搜索树

/**
 * 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:
    TreeNode* build(int l, int r, vector<int>&nums){
        if(l>r)return 0;
        int mid=l+r>>1;
        TreeNode *root=new TreeNode(nums[mid]);
        root->left=build(l,mid-1,nums);
        root->right=build(mid+1,r,nums);
        return root;
    }
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        return build(0,nums.size()-1,nums);
    }
};