两数之和的答案，但是报错了

Question

怎么解决，运行不了，不知道vector的用法
代码
class Solution {
public:
vector twoSum(vector& nums, int target) {
unordered_map<int, int> hashtable;
for (int i = 0; i < nums.size(); ++i) {
auto it = hashtable.find(target - nums[i]);
if (it != hashtable.end()) {
return {it->second, i};
}
hashtable[nums[i]] = i;
}
return {};
}
};

Answer 1

#include<vector>
using namesapce std;