Java8

public static List<Integer> jimOrders(List<List<Integer>> orders) {
// Write your code here
List<Integer> list=new ArrayList<>();
Map<Integer,Integer> map=new HashMap<>();
int x;
for(int i=0;i<orders.size();i++){
    x=orders.get(i).get(0)+orders.get(i).get(1);
    map.put(i+1, x);
}

   //map is sorted by values
  final Map<Integer, Integer> sortedByTime = map.entrySet()
            .stream()
            .sorted(Map.Entry.comparingByValue())
            .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue, (e1, e2) -> e1, LinkedHashMap::new)); 


 for(int i : sortedByTime.keySet()){
     list.add(i);
 }

return list; }