class Solution {
public:
    vector<int> twoSum(vector<int>& nums, int target) {
        unordered_map<int,int> numsMap;
        vector<int> result;
        int length = nums.size();

        for (int i = 0; i<length; i++) {
            numsMap[nums[i]] = i;
        }

        for (int i = 0; i<length; i++) {
            /*  If we call find(), it will return the last Key-Value
                ex: numsMap[6] = 3;
                    numsMap[6] = 6;
                    numsMap[6] = 1;
                ==> numsMap.find(6) will return 'numsMap[6] = 1'
             */
            auto it = numsMap.find(target-nums[i]);
            /* Consider this case:
               [3, 2, 4] , target = 6

               If we don't add 'it->second > i'
               it will return [0, 0]
               because numsMap.find(3) return 'numsMap[3] = 0'
             */
            if (it != numsMap.end() && it->second>i) {
                result.push_back(i);
                result.push_back(it->second);
                break;
            }
        }
        return result;
    }
};