#advent of code 2020
#day 24
# https://www.redblobgames.com/grids/hexagons/
# nested ifs in CheckAdjacent function aren't really slower than
# making it a function, so i'm leaving it bc its more readable that way

def CheckAdjacent(point, blackset):
	black = 0;
	py,px,pz = point;
	for dkey in directions:
		dx,dy,dz = directions[dkey];
		p = (py+dy,px+dx, pz+dz);
		if p in blackset: 
			black += 1;
	
	if point in blackset:
		if black == 0 or black > 2:
			return False;
		else: 
			return True;
	else:
		if black == 2:
			return True;
		else:
			return False;

tilesteps = [];

PuzzleInput = open("24.in","r")
for line in PuzzleInput:
	line = line.replace("\n","");
	instructions = [];
	i = 0;
	while i < len(line):
		if line[i] in ["n","s"]:
			instructions.append(line[i:i+2]);
			i += 2;
		else:
			instructions.append(line[i]);
			i += 1;
	tilesteps.append(instructions);
PuzzleInput.close();

directions = dict();
directions["e"] = (1,0,-1);
directions["w"] = (-1,0,1);
directions["ne"] = (1,-1,0);
directions["nw"] = (0,-1,1);
directions["sw"] = (-1,1,0);
directions["se"] = (0,1,-1);

grid = dict();
# 0 - white
# 1 - black

for tilestep in tilesteps:
	p = (0,0,0);
	for step in tilestep:
		py,px,pz = p;
		dy,dx,dz = directions[step];
		p = (py+dy,px+dx, pz+dz);
	grid[p] = ( grid.get(p,0) + 1)%2;

blacks = set();
part1 = 0;
for g in grid:
	if grid[g] == 1: 
		part1 += 1;
		blacks.add(g);

print("part 1 =", part1);

days = 100;
for day in range(days):
	NewBlacks = set();
	for b in blacks:
		if CheckAdjacent(b,blacks): NewBlacks.add(b);
		for coord in directions.values():
			n = (b[0] + coord[0],b[1] + coord[1],b[2] + coord[2]);
			if CheckAdjacent(n,blacks): NewBlacks.add(n);
	blacks = set();
	blacks.update(NewBlacks);

part2 = len(blacks);
print("part 2 =", part2);