سلام.
static void Main(string[] args)
{
int[] values = { 1, 2, 4, 5, 0, 12, 1 };
int firsMaxValueIndex = Array.IndexOf(values, values.Max());
int SecondMaxValue = 0;
for (int i = 0; i < values.Length; ++i)
{
if (i == firsMaxValueIndex)
continue;
if (values[i] > values[SecondMaxValue])
SecondMaxValue = i;
}
Console.Write(firsMaxValueIndex + " " + SecondMaxValue);
Console.ReadKey();
}