Leetcode1.Two_Sum

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int, int>hash;
        for (int i = 0; i < nums.size(); i++)
        {
            if (hash.find(target - nums[i]) != hash.end())
                return vector<int>{hash[target - nums[i]], i};
            else
                hash.insert(make_pair(nums[i], i));
        }
    }
};