Two Sum

c++

class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        if (nums.size() <= 1) return vector<int>();
        unordered_map<int, int> dict;
        for (int i = 0; i < nums.size(); ++i) {
            dict[nums[i]] = i;
        }
        vector<int> res;
        for (int i = 0; i < nums.size(); ++i) {
            int tmp = target - nums[i];
            if ((dict.find(tmp) != dict.end()) && (dict[tmp] != i)) {
                res.push_back(i);
                res.push_back(dict[tmp]);
                return res;
            }
        }
        return res;
    }
};