108 Convert Sorted Array to Binary Search Tree 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* sortedArrayToBST(vector<int>& nums) {
        int n=nums.size();
        if(n==0||nums.empty())
        {
            return nullptr;
        }
        if(n==1)
        {
            return new TreeNode(nums[0]);
        }
        int mid=n/2;
        vector<int> left(nums.begin(),nums.begin()+mid);
        vector<int> right(nums.begin()+mid+1,nums.end());
        TreeNode* root=new TreeNode(nums[mid]);
        root->left=sortedArrayToBST(left);
        root->right=sortedArrayToBST(right);
        return root;
    }
};