public void ExecuteIntcodeProgram_HappyPath_ReturnsExpectedResult(IntcodeProgramState program, IntcodeProgramState expectedResult)
{
var result = IntcodeProgramExecutor.ExecuteIntcodeProgram(program);
result.Codes.Should().BeEquivalentTo(expectedResult.Codes);
result.CurrentInstruction.Should().Be(expectedResult.CurrentInstruction);
}
private static IntcodeProgramState ExecuteIntcodeProgramStep(IntcodeProgramState program)
{
var current = program.CurrentInstruction;
var opCode = program.Codes[current++];
if (opCode == 99)
{
return(program);
}
Func <int, int, int> op = opCode switch
{
1 => (a, b) => a + b,
2 => (a, b) => a * b,
_ => throw new Exception($"Unknown op code {opCode}")
};
var a = program.Codes[program.Codes[current++]];
var b = program.Codes[program.Codes[current++]];
var resultIndex = program.Codes[current++];
var result = op(a, b);
var newCodes = program.Codes.SetItem(resultIndex, result);
return(new IntcodeProgramState()
{
Codes = newCodes,
CurrentInstruction = current
});
}
}
public static IntcodeProgramState ExecuteIntcodeProgram(IntcodeProgramState program)
{
while (!Done(program))
{
program = ExecuteIntcodeProgramStep(program);
}
return(program);
}
private static bool Done(IntcodeProgramState program) => program.Codes[program.CurrentInstruction] == 99;
