1. Two Sum
class Solution {
public:
vector<int> twoSum(vector<int>& nums, int target) {
int num;
num = nums.size();
vector<int> index;
for (int i = 0; i < num; i++)
{
for(int j = i+1; j < num; j++)
{
if(nums[i]+nums[j]==target)
{
index.push_back(i);
index.push_back(j);
}
}
}
return index;
}
};