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) {
        vector <int> answer;
        for (int i = 0; i< nums.capacity(); i++) {
            int adder = nums.at(i);
            for (int j = i + 1; j < nums.capacity(); j++) {
                if (adder + nums.at(j) == target) {
                    answer.push_back(i);
                    answer.push_back(j);
                    break;
                }
            }
        }
        return answer;
    }
};