private async Task <(Dictionary <(int, int), char>, (int, int))> GetMapAsync()
{
var map = new Dictionary <(int, int), char>();
var pos = (0, 0);
var tar = pos;
var dir = N;
var input = Channel.CreateUnbounded <BigInteger>();
var intcode = new IntcodeComputer(_input)
{
Input = () => input.Reader.ReadAsync().AsTask()
};
intcode.Output = async status =>
{
switch ((int)status)
{
case 0: // hit wall
map[Step(pos, dir)] = '#';
dir = dir switch
{
N => W,
W => S,
S => E,
E => N,
_ => throw new Exception("dir?"),
};
await input.Writer.WriteAsync(dir);
break;
case 1: // moved
pos = Step(pos, dir);
map[pos] = '.';
dir = dir switch
{
N when !IsWall(Step(pos, E)) => E,
N => N,
W when !IsWall(Step(pos, N)) => N,
W => W,
S when !IsWall(Step(pos, W)) => W,
S => S,
E when !IsWall(Step(pos, S)) => S,
E => E,
_ => throw new Exception("dir?"),
};
await input.Writer.WriteAsync(dir);
if (pos == default && tar != default)
{
intcode.Halt();
}
break;
case 2: // found it
tar = Step(pos, dir);
goto case 1;
}
};
await input.Writer.WriteAsync(dir);
await intcode.RunAsync();
return(map, tar);
bool IsWall((int, int) pos) => map.TryGetValue(pos, out var c) && c == '#';
}
