Method 1: violence to resolve (the easiest)
class Solution { public: vector<int> twoSum(vector<int>& nums, int target) { vector<int> v; for(int i=0;i<nums.size();i++){ for(int j=i+1;j<nums.size();j++){ if(nums[i]+nums[j]==target){ v.push_back(i); v.push_back(j); } } } returnv; } };
Method 2: dictionary / hash