Solved part 2 of day 12

12/part1.py

@@ -42,9 +42,6 @@ if __name__ == "__main__":
 			dirX, dirY = 0, 0
 			if opcode == "F":
 				dirX, dirY = degreesToOffset(currentDirection)
-			elif opcode == "B":
-				dirX, dirY = degreesToOffset(currentDirection)
-				dirX, dirY = -dirX, -dirY
 			else:
 				dirX, dirY = directionToOffset(opcode)
 			currentX += dirX * value

12/part2.py

@@ -0,0 +1,53 @@
+import math
+
+def getInstructions(filename):
+	with open(filename, "r") as f:
+		return [(line[0], int(line[1:])) for line in f.read().split()]
+
+def directionToOffset(direction):
+	if direction == "E":
+		return (1, 0)
+	elif direction == "N":
+		return (0, -1)
+	elif direction == "W":
+		return (-1, 0)
+	elif direction == "S":
+		return (0, 1)
+	else:
+		raise Exception(f"Invalid cardinal direction '{direction}'")
+
+def degreesToOffset(degrees):
+	degrees %= 360
+	if degrees == 0:
+		return (1, 0)
+	elif degrees == 90:
+		return (0, -1)
+	elif degrees == 180:
+		return (-1, 0)
+	elif degrees == 270:
+		return (0, 1)
+	else:
+		raise Exception(f"Invalid degrees '{degrees}'")
+
+def rotatePoint(x, y, angle):
+	angleRadians = math.radians(angle)
+	return round(x * math.cos(angleRadians) - y * math.sin(angleRadians)), \
+				 round(x * math.sin(angleRadians) + y * math.cos(angleRadians))
+
+if __name__ == "__main__":
+	currentX, currentY = 0, 0
+	waypointX, waypointY = 10, -1
+	for instruction in getInstructions("input.txt"):
+		opcode, value = instruction
+		if opcode == "F":
+			currentX += waypointX * value
+			currentY += waypointY * value
+		elif opcode == "L":
+			waypointX, waypointY = rotatePoint(waypointX, waypointY, -value)
+		elif opcode == "R":
+			waypointX, waypointY = rotatePoint(waypointX, waypointY, value)
+		else:
+			offX, offY = directionToOffset(opcode)
+			waypointX += offX * value
+			waypointY += offY * value
+	print(abs(currentX) + abs(currentY))