GetFreshestBeers

gistfile1.txt

private class Bottle
        {
            public int ID { get; set; }
            public DateTime BottledDate { get; set; }
        }

        [TestMethod()]
        public void JoinOnMaxDate()
        {
            List<int> bottleNumbers = new List<int>(6) { 1, 2, 3, 4, 5, 6 };
            List<Bottle> bottles = new List<Bottle>(7) {
                new Bottle {ID =1,BottledDate=DateTime.Now.AddDays(-7) },
                new Bottle {ID =1,BottledDate=DateTime.Now.AddDays(-6) },
                new Bottle {ID =2,BottledDate=DateTime.Now.AddDays(-7) },
                new Bottle {ID =3,BottledDate=DateTime.Now.AddDays(-7) },
                new Bottle {ID =4,BottledDate=DateTime.Now.AddDays(-7) },
                new Bottle {ID =5,BottledDate=DateTime.Now.AddDays(-7) },
                new Bottle {ID =6,BottledDate=DateTime.Now.AddDays(-7) }
                };

            var fresherBottles = bottles.Join(
                    bottleNumbers,
                    b => b.ID,
                    bn => bn,
                    (b2, r) => b2)
                .OrderBy(x => x.BottledDate).GroupBy(x => x.ID)
                .Select(g => g.First())
                .ToList();

            fresherBottles.ForEach(b => Debug.WriteLine(
              string.Format("Bottle {0}, bottled on {1}", b.ID, b.BottledDate.ToLocalTime()))); 

        }