// == PART II
/// <summary>A brute-force algorithm to systematically try all possible input pairs
/// until we find the one that gave the desired output (we can determine a
/// finished set of possible candidates since we know that each number is in the
/// [0, 99] range).</summary>
/// <param name="inputs">List of integers to execute as an Intcode program.</param>
/// <param name="wantedOutput">Desired output of the program.</param>
/// <returns>Specific checksum that matches the desired output.</returns>
static int FindChecksum(int[] inputs, int wantedOutput)
{
// prepare program
IntcodeProgram program = new IntcodeProgram(inputs);
for (int noun = 0; noun < 100; noun++) // range is [0, 100[ = [0, 99]
{
for (int verb = 0; verb < 100; verb++)
{
// reset program to initial state
program.Reset();
// set up noun and verb
program.Program[1] = noun;
program.Program[2] = verb;
// run and compare result
program.Run();
if (program.Program[0] == wantedOutput)
{
return(100 * noun + verb);
}
}
}
return(-1);
}
// [ Computation functions ]
// -------------------------
// == PART I
/// <summary>Executes the Intcode program on the provided inputs and computes the final
/// result.</summary>
/// <param name="inputs">List of integers to execute as an Intcode program.</param>
/// <param name="restoreGravityAssist">Whether or not to restore the gravity assist
/// by modifying the input program.</param>
/// <returns>Final output of the program.</returns>
static int ProcessInputs(int[] inputs, bool restoreGravityAssist = false)
{
// restore gravity assist?
if (restoreGravityAssist)
{
inputs[1] = 12;
inputs[2] = 2;
}
// create and execute the program
IntcodeProgram program = new IntcodeProgram(inputs);
program.Run();
// isolate final result
return(program.Program[0]);
}
