If current index `i`

is already bigger than current min index sum, exit loop right away.

```
vector<string> findRestaurant(vector<string>& list1, vector<string>& list2) {
if (list1.size() < list2.size()) return findRestaurant(list2, list1);
// always convert shorter vector to hash map (save space)
unordered_map<string, int> map2; int i2 = -1;
for (auto& s : list2) map2[s] = ++i2;
vector<string> res;
for (size_t i = 0, minSum = INT_MAX; i < min(minSum+1, list1.size()); ++i) {
int sum = map2.count(list1[i])? i + map2[list1[i]] : INT_MAX;
if (sum < minSum) res = {list1[i]}, minSum = sum;
else if (sum == minSum) res.push_back(list1[i]);
}
return res;
}
```