#advent of code 2018 
#day 13
#part 1 and part 2

#I got it working the first time, but I was getting a wrong answer for actual input
#turns out I made a mistake in calculations for the crossroads for turn-left and turn-right
#i hastily scrambled a set of 2 equations for X and Y coordinates 
#and it costed me time wasted on debugging 
#for each round I was drawing the current layout of the map with a single cart 
#I noticed that at crossroads it was doing a turn-left, straight, turn-left 
#(instead of right for 3rd crossroads)
#I followed my equations by *slowly* calculating them on paper 
#and found out that I had wrong signs for Y coordinate
#fun puzzle nonetheless
#comment for part2
#i had a bit of an issue with getting it working properly
#at this moment, the part2 is calculated correctly, but part1 was off
#I cleaned up the code a bit and managed to solve this, so both parts are in the same file

f = open("input.txt",'r');
Testing = False;
#Testing = True;
if Testing:
	f.close();
	f = open("testinput.txt",'r');
	
class trackpoint:
	def __init__(self, sign, x, y):
		self.sign = sign;
		self.positionX = x;
		self.positionY = y;
	def __str__(self):
		return self.sign;
		
class hline(trackpoint):
	def __init__(self, sign, x, y):
		trackpoint.__init__(self, sign, x, y);
	def GiveSteps(self, cart_x, cart_y, cartid):
		#left or right
		x_next = self.positionX + (self.positionX - cart_x); 
		y_next = self.positionY + (self.positionY - cart_y); 
		return [x_next, y_next];	
		
class vline(trackpoint):
	def __init__(self, sign, x, y):
		trackpoint.__init__(self, sign, x, y);
	def GiveSteps(self, cart_x, cart_y, cartid):
		#up or down
		x_next = self.positionX + (self.positionX - cart_x); 
		y_next = self.positionY + (self.positionY - cart_y); 
		return [x_next, y_next];
		
class turnleft(trackpoint):
	def __init__(self, sign, x, y):
		trackpoint.__init__(self, sign, x, y);
	def GiveSteps(self, cart_x, cart_y, cartid):
		x_next = self.positionX - (cart_y - self.positionY); 
		y_next = self.positionY - (cart_x - self.positionX);
		return [x_next, y_next];
		
class turnright(trackpoint):
	def __init__(self, sign, x, y):
		trackpoint.__init__(self, sign, x, y);
	def GiveSteps(self, cart_x, cart_y, cartid):
		x_next = self.positionX + (cart_y - self.positionY); 
		y_next = self.positionY + (cart_x - self.positionX);
		return [x_next, y_next];
		
class crossroads(trackpoint):
	def __init__(self, sign, x, y):
		trackpoint.__init__(self, sign, x, y);
		self.CartRegistry = {};
	def GiveSteps(self, cart_x, cart_y, cartid):
		#number of crossroads is updated before this function is called, thats why it starts from 1
		if (cartid%3 == 1):
			#turn left
			x_next = self.positionX - (cart_y - self.positionY); 
			y_next = self.positionY + (cart_x - self.positionX); 
		elif (cartid%3 == 2): 
			#go straight 
			x_next = self.positionX + (self.positionX - cart_x); 
			y_next = self.positionY + (self.positionY - cart_y); 
		elif (cartid%3 == 0): 
			#turn right
			x_next = self.positionX + (cart_y - self.positionY); 
			y_next = self.positionY - (cart_x - self.positionX); 
		return [x_next, y_next];

class minecart: 
	def __init__(self, sign, x, y, cart_id):
		self.posX = x;
		self.posY = y;
		self.XroadsEncountered = 0;
		self.nextstepX = x;
		self.nextstepY = y;
		self.Cart_ID = cart_id;
		self.notHit = True;
		if (sign == '>'):
			self.prevX = x-1;
			self.prevY = y;
		if (sign == '<'):
			self.prevX = x+1;
			self.prevY = y;
		if (sign == 'v'):
			self.prevX = x;
			self.prevY = y-1;
		if (sign == '^'):
			self.prevX = x;
			self.prevY = y+1;
	def cartmove(self, nextX, nextY):
		self.nextstepX = nextX;
		self.nextstepY = nextY;
		self.prevX = self.posX;
		self.prevY = self.posY;
		self.posX = self.nextstepX;
		self.posY = self.nextstepY;
	def ReadCoords(self):
		return [self.posX, self.posY];
	def CheckMatch(self, OtherCoords):
		return (self.posX == OtherCoords[0] and self.posY == OtherCoords[1]);
	def IsXroads(self, currentsign):
		if (currentsign == "+"):
			self.XroadsEncountered += 1;

trackmap = [];

for l in f:
	subline = [];
	l.replace("\n", "");
	for c in l:
		subline.append(c);
	trackmap.append(subline.copy());

cartlist = [];
cartid_counter = 10;

TMSize_C = len(trackmap);
TMSize_R = len(trackmap[0]) -1;
#RETREIVING MINECARTS AND REPLACING SIGNS ON THE MAP
for c in range(TMSize_C):
	for r in range(TMSize_R):
		if (trackmap[c][r] == '^' or trackmap[c][r] == 'v' or trackmap[c][r] == '>' or trackmap[c][r] == '<'):
			cartlist.append( minecart(trackmap[c][r], r, c, cartid_counter) );
			cartid_counter += 1;
			if (trackmap[c][r] == '^' or trackmap[c][r] == 'v'):
				trackmap[c][r] = '|';
			if (trackmap[c][r] == '>' or trackmap[c][r] == '<'):
				trackmap[c][r] = '-';

cartlist = sorted(cartlist, key=lambda x: (x.posY, x.posX));
newmap = [];

for c in range(TMSize_C):
	templine = [];
	for r in range(TMSize_R):
		if (trackmap[c][r] == ' '):
			templine.append( trackpoint(trackmap[c][r], r, c) );
		elif (trackmap[c][r] == '-'):
			templine.append( hline(trackmap[c][r], r, c) );
		elif (trackmap[c][r] == '|'):
			templine.append( vline(trackmap[c][r], r, c) );
		elif (trackmap[c][r] == '/'):
			templine.append( turnright(trackmap[c][r], r, c) );
		elif (trackmap[c][r] == '\\'):
			templine.append( turnleft(trackmap[c][r], r, c) );
		elif (trackmap[c][r] == '+'):
			templine.append( crossroads(trackmap[c][r], r, c) );
	newmap.append( templine.copy() );

roundcounter = 0;
part1 = None;
p1round = 0;

while (len(cartlist) > 1):
	roundcounter += 1;
	cartlist = sorted(cartlist, key=lambda x: (x.posY, x.posX));
	for mc in cartlist:
		NextSteps = [];
		mc.IsXroads(newmap[mc.posY][mc.posX].sign);
		NextSteps = newmap[mc.posY][mc.posX].GiveSteps(mc.prevX, mc.prevY, mc.XroadsEncountered);
		mc.cartmove(NextSteps[0],NextSteps[1]);
		MatchCounter = 0;
		for mc2 in cartlist:
			if mc.Cart_ID != mc2.Cart_ID:
				mc.notHit  = not mc.CheckMatch( mc2.ReadCoords() );
				mc2.notHit = not mc2.CheckMatch( mc.ReadCoords() );
			if part1 == None and mc.notHit == False:
				part1 = mc.ReadCoords();
				p1round = int(roundcounter);
				#print("part 1 = ",part1, "\t after", roundcounter, "rounds");
			cartlist = [c for c in cartlist if c.notHit];

part2 = cartlist[0].ReadCoords();
print("part 1 = ",part1, "\t after", p1round, "rounds");
print("part 2 = ",part2, "\t after", roundcounter, "rounds");