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+#advent of code 2018 
+#day 18
+#part 1 and part 2
+
+#at first I thought I can find the loop by simply registering when a value "part2" is repeated once
+#(kind of like in an earlier puzzle for that year)
+#then I had a correct idea how to find the pattern, 
+#but didn't really know how to implement it efficently
+#pattern recognition is an implementation of solution provided by Michael Fogleman
+#adjusted to my current code
+#another issue I had was that I resumed the calculations for part 2 from the state after 10 minutes (part1)
+#I needed to save the initial state and then start over
+#could probably reduce the code to single loop instead of two separate loops for each part
+
+f = open("input.txt",'r');
+Testing = False;
+#Testing = True; 
+if Testing:
+	f.close();
+	f = open("testinput.txt",'r');
+
+size = 50;
+if Testing: size = 10;
+
+#part 1
+
+CurrentState = {};
+
+for r,l in enumerate(f):
+	#print(len(l));
+	for c,a in enumerate(l):
+		CurrentState.update({(r,c):a});
+InitialState = CurrentState.copy();
+f.close();
+
+for x in range(size):
+	for y in range(size):
+		print(CurrentState[(x,y)],end="");
+	print();
+
+#check if each adjacent position is still within grid range
+def GetAdjacent(Cords):
+	Adjacent = [];
+	if (Cords[0] -1 >= 0 and Cords[1]-1 >=0):
+		Adjacent.append( (Cords[0] -1,Cords[1]-1) );
+	if (Cords[0] -1 >= 0):
+		Adjacent.append( (Cords[0] -1,Cords[1]) );
+	if (Cords[0] -1 >= 0 and Cords[1]+1 < size):
+		Adjacent.append( (Cords[0] -1,Cords[1]+1) );
+	if (Cords[1]+1 < size):
+		Adjacent.append( (Cords[0],Cords[1]+1) );
+	if (Cords[1]-1 >= 0):
+		Adjacent.append( (Cords[0],Cords[1]-1) );
+	if (Cords[0] +1 < size and Cords[1]-1 >=0):
+		Adjacent.append( (Cords[0] +1,Cords[1]-1) );
+	if (Cords[0] +1 < size):
+		Adjacent.append( (Cords[0] +1,Cords[1]) );
+	if (Cords[0] +1 < size and Cords[1]+1 < size):
+		Adjacent.append( (Cords[0] +1,Cords[1]+1) );
+	return Adjacent;
+	
+def GetAcres(area, adj):
+	acres = [];
+	for c in adj:
+		acres.append(area[c]);
+	return acres;
+
+def ChangeState(area, Cords):
+	s = area[Cords];
+	adj = GetAdjacent(Cords);
+	Acres = GetAcres(area, adj);
+	if (s == "." and Acres.count("|")>=3):
+		s = "|";
+	elif (s == "|" and Acres.count("#")>=3):
+		s = "#";
+	elif (s == "#" and Acres.count("#")>=1 and Acres.count("|")>=1):
+		s = "#";
+	elif (s == "#"):
+		s = ".";
+	return s;
+
+SimTime = 10; #minutes
+
+InitialState = CurrentState.copy();
+for t in range(SimTime):
+	NextState = {};
+	for x in range(size):
+		for y in range(size):
+			NextState.update({(x,y):ChangeState(CurrentState,(x,y))});
+	CurrentState = NextState.copy();
+	'''
+	print("MINUTE ",t);
+	for x in range(size):
+		for y in range(size):
+			print(CurrentState[(x,y)],end="");
+		print();
+	print();
+	'''
+summary = list(CurrentState.values());
+
+woods = summary.count("|");
+lumbs = summary.count("#");
+part1 = woods*lumbs;
+print("part 1 = ", part1);
+
+#part 2
+
+SimTime2 = 1000000000; #minutes for part2
+values = {};
+prev = 0;
+
+CurrentState = InitialState.copy();
+for t in range(1,SimTime2):
+	NextState = {};
+	for x in range(size):
+		for y in range(size):
+			NextState.update({(x,y):ChangeState(CurrentState,(x,y))});
+	CurrentState = NextState.copy();
+	summary = list(CurrentState.values());
+	woods = summary.count("|");
+	lumbs = summary.count("#");
+	part2 = woods*lumbs;
+	loop = t - values.get(part2,0);
+	if (loop == prev):
+		if SimTime2%loop == t%loop:
+			break;
+	values[part2]=t;
+	prev = loop;
+
+print("part 2 = ", part2);
+