C#

public static List<int> jimOrders(List<List<int>> orders)
{
    var res= new List<int>();
    Dictionary<int,int> map = new Dictionary<int,int>();

    for (int i = 0; i < orders.Count;i++)
    {
        map[i+1] = orders[i][0] + orders[i][1];

    }

    var mapSort = map.OrderBy(x => x.Value).ToList();
    foreach (var item in mapSort)
    {
        res.Add(item.Key);
    }
    return res;
}