var ret = new int[100];
for (int i = 0; i < ret.Length; i++)
ret[i] = new Random().Next(1,999);
ret = ret.AddRandom(0, 5);
........................
public static class Extern {
public static int[] AddRandom(this int[] arr,int value, int count) {
while (arr.Count(c=>c==value)<=count)
{
int i = new Random().Next(0, arr.Length);
if (arr[i] != value) arr[i] = value;
}
return arr;
}