[LintCode] Two Sum 两数之和

class Solution {
public:
    /*
     * @param numbers : An array of Integer
     * @param target : target = numbers[index1] + numbers[index2]
     * @return : [index1+1, index2+1] (index1 < index2)
     */
    vector<int> twoSum(vector<int> &nums, int target) {
        unordered_map<int, int> m;
        for (int i = 0; i < nums.size(); ++i) m[nums[i]] = i;
        for (int i = 0; i < nums.size(); ++i) {
            int t = target - nums[i];
            if (m.count(t) && m[t] != i) {
                return {i + 1, m[t] + 1};
            }
        }
        return {};
    }
};