以下代码的逻辑非常简单，对列表进行排序并检查天数增量是否大于1，如果大于1，则为其创建一个新组：

创建测试日期：

//Dates for testing
 List<DateTime> dates = new List<DateTime>()
 { 
      new DateTime(2013,12,31),
      new DateTime(2014,2,2),
     new DateTime(2014,1,1),
     new DateTime(2014,1,2),
     new DateTime(2014,2,1),               
     new DateTime(2014,2,16),
     new DateTime(2014,3,13),
 };

并创建组：

 dates.Sort();
 //this will hold the resulted groups
 var groups = new List<List<DateTime>>();
 // the group for the first element
 var group1 = new List<DateTime>(){dates[0]};
 groups.Add(group1);

 DateTime lastDate = dates[0];
 for (int i = 1; i < dates.Count; i++)
 {
     DateTime currDate = dates[i];
     TimeSpan timeDiff = currDate - lastDate;
     //should we create a new group?
     bool isNewGroup = timeDiff.Days > 1;
     if (isNewGroup)
     {
         groups.Add(new List<DateTime>());
     }
     groups.Last().Add(currDate);
     lastDate = currDate;
 }

和输出：