LeetCode 1. Two Sum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:
Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

class Solution {public:    vector<int> twoSum(vector<int>& nums, int target) {        unordered_map <int, int >  map;        vector <int > ans(2);        for (int i = 0; i < nums.size(); ++i)        {            if (map.find(target - nums[i]) != map.end())            {                ans[0]= map[target - nums[i]];                ans[1]=i;                break;             }            else            {                map[nums[i]] = i;             }        }        return ans;    }};