一组数中求出重复的数
如一组数中有1、4、5、4、3、5、1
结果重复的数为：1、4、5

[解决办法]

C# code

 int[] int_array = new int[] {1,4,5,4,3,5,1 };            int[] repeat_array = int_array.GroupBy(a=>a).Where(a=>a.Count()>1).Select(a=>a.Key).ToArray();            /*            [0]    1    int            [1]    4    int            [2]    5    int             */
[解决办法]
C# code
            int[] array = new int[] { 1, 4, 5, 4, 3, 5, 1 };            int[] newArray = (from i in array                    group i by i into grouped                    where grouped.Count() > 1                    select grouped.Key).ToArray();