public static void Execute()
{
string[] inputs = File.ReadAllLines(@"2020\Data\day13.txt");
List <string> busServicesBeforeParse = inputs[1].Split(',').ToList();
Dictionary <int, int> timesAfterFirstBus = new Dictionary <int, int>();
for (int index = 0; index < busServicesBeforeParse.Count; index++)
{
if (busServicesBeforeParse[index] == "x")
{
continue;
}
timesAfterFirstBus.Add(int.Parse(busServicesBeforeParse[index]), index);
}
List <Congruence> congruences = new List <Congruence>();
foreach (var input in timesAfterFirstBus)
{
congruences.Add(new Congruence {
M = input.Key, A = input.Value == 0 ? 0 : input.Key - input.Value
});
}
long totalM = congruences.Mult();
long a = 0;
foreach (var congruence in congruences)
{
long ai = congruence.A;
long ni = CalculateN(congruence.M, totalM);
long ui = CalculateU(ni, congruence.M);
a += (ai * ni * ui);
}
Congruence totalCongruence = new Congruence {
A = a % totalM, M = congruences.Mult()
};
Console.WriteLine(totalCongruence.A);
}
public static void congruence_test()
//****************************************************************************80
//
// Purpose:
//
// CONGRUENCE_TEST tests CONGRUENCE.
//
// Licensing:
//
// This code is distributed under the GNU LGPL license.
//
// Modified:
//
// 07 November 2012
//
// Author:
//
// John Burkardt
//
{
const int TEST_NUM = 20;
int[] a_test =
{
1027, 1027, 1027, 1027, -1027,
-1027, -1027, -1027, 6, 0,
0, 0, 1, 1, 1,
1024, 0, 0, 5, 2
}
;
int[] b_test =
{
712, 712, -712, -712, 712,
712, -712, -712, 8, 0,
1, 1, 0, 0, 1,
-15625, 0, 3, 0, 4
}
;
int[] c_test =
{
7, -7, 7, -7, 7,
-7, 7, -7, 50, 0,
0, 1, 0, 1, 0,
11529, 1, 11, 19, 7
}
;
bool error = false;
int test_i;
Console.WriteLine("");
Console.WriteLine("CONGRUENCE_TEST");
Console.WriteLine(" CONGRUENCE solves a congruence equation:");
Console.WriteLine(" A * X = C mod ( B )");
Console.WriteLine("");
Console.WriteLine(" I A B C X Mod ( A*X-C,B)");
Console.WriteLine("");
for (test_i = 1; test_i < TEST_NUM; test_i++)
{
int a = a_test[test_i];
int b = b_test[test_i];
int c = c_test[test_i];
int x = Congruence.congruence(a, b, c, ref error);
switch (error)
{
case true:
Console.WriteLine(" "
+ test_i.ToString().PadLeft(2) + " "
+ a.ToString().PadLeft(10) + " "
+ b.ToString().PadLeft(10) + " "
+ c.ToString().PadLeft(10) + " "
+ "(An error occurred)");
break;
default:
{
int result = b != 0 ? typeMethods.i4_modp(a * x - c, b) : 0;
Console.WriteLine(" "
+ test_i.ToString().PadLeft(2) + " "
+ a.ToString().PadLeft(10) + " "
+ b.ToString().PadLeft(10) + " "
+ c.ToString().PadLeft(10) + " "
+ x.ToString().PadLeft(10) + " "
+ result.ToString().PadLeft(10) + "");
break;
}
}
}
}
