Find Duplicate value from array

Please refer below code.

C#

int[] arr = new int[13]
        {
        1,1,2,6,7,7,8,0,9,7,6,3,4
        };
int[] duplicateValues = arr.GroupBy(x => x).Where(group => group.Count() > 1).Select(y => y.Key).ToArray();

I hope this will help you out.