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> ans(2);
        for(int i = 0; i < nums.size(); i++) {
            for(int j = i + 1; j < nums.size(); j++) {
                if(nums[i] + nums[j] == target) {
                    ans[0] = i;
                    ans[1] = j;
                    return ans;
                }
            }
        }
    }
};