Day 12, part 2

2020/12/main.py

@@ -1,8 +1,19 @@
-class Ferry:
+import math
+
+class Waypoint:
 	def __init__(self):
 		self.heading = 90  # east
 		self.pos_north = 0
 		self.pos_east = 0
+		self.commands = {
+			"N": self.move_north,
+			"S": self.move_south,
+			"E": self.move_east,
+			"W": self.move_west,
+			"L": self.rotate_left,
+			"R": self.rotate_right,
+			"F": self.move_forward,
+		}
 
 	def load(self, filename):
 		with open(filename, "r", encoding="utf-8") as f:
@@ -10,30 +21,27 @@ class Ferry:
 				data = line.rstrip()
 				self.process(data)
 
-	def rotate(self, degrees):
-		self.heading += degrees
-		while self.heading < 0:
-			self.heading += 360
-		while self.heading >= 360:
-			self.heading -= 360
-
-	def process(self, input):
-		command = input[:1]
-		value = int(input[1:])
-
-		if command == "N":
+	def move_north(self, value):
 		self.pos_north += value
-		elif command == "S":
+
+	def move_south(self, value):
 		self.pos_north -= value
-		elif command == "E":
+
+	def move_east(self, value):
 		self.pos_east += value
-		elif command == "W":
+
+	def move_west(self, value):
 		self.pos_east -= value
-		elif command == "L":
-			self.rotate(-value)
-		elif command == "R":
-			self.rotate(value)
-		elif command == "F":
+
+	def rotate_left(self, degrees):
+		self.heading -= degrees
+		self.__fix_heading()
+
+	def rotate_right(self, degrees):
+		self.heading += degrees
+		self.__fix_heading()
+
+	def move_forward(self, value):
 		if self.heading == 0:
 			self.pos_north += value
 		elif self.heading == 90:
@@ -44,16 +52,79 @@ class Ferry:
 			self.pos_east -= value
 		else:
 			raise Exception(self.heading)
-		else:
-			raise Exception(command)
 
-		print(input, self.pos_east, self.pos_north)
+	def __fix_heading(self):
+		while self.heading < 0:
+			self.heading += 360
+		while self.heading >= 360:
+			self.heading -= 360
+
+	def process(self, input):
+		cchar = input[:1]
+		value = int(input[1:])
+		command = self.commands[cchar]
+		command(value)
 
 	def get_md(self):
 		return abs(self.pos_east) + abs(self.pos_north)
 
+
+class Ship:
+	def __init__(self):
+		self.waypoint = Waypoint()
+		self.pos_north = 0
+		self.pos_east = 0
+		self.commands = {
+			"F": self.move_forward,
+			"L": self.rotate_left,
+			"R": self.rotate_right,
+		}
+
+	def load(self, filename):
+		with open(filename, "r", encoding="utf-8") as f:
+			for line in f:
+				data = line.rstrip()
+				self.process(data)
+
+	def process(self, input):
+		cchar = input[:1]
+		value = int(input[1:])
+		if cchar in self.commands:
+			command = self.commands[cchar]
+			command(value)
+		else:
+			self.waypoint.process(input)
+
+	def move_forward(self, value):
+		self.pos_north += self.waypoint.pos_north * value
+		self.pos_east += self.waypoint.pos_east * value
+
+	def rotate_right(self, degrees):
+		self.rotate_left(-degrees)
+
+	def rotate_left(self, degrees):
+		radians = degrees / 180 * math.pi
+		c = math.cos(radians)
+		s = math.sin(radians)
+		e = c * self.waypoint.pos_east - s * self.waypoint.pos_north
+		n = s * self.waypoint.pos_east + c * self.waypoint.pos_north
+		self.waypoint.pos_east = round(e)
+		self.waypoint.pos_north = round(n)
+
+	def get_md(self):
+		return abs(self.pos_east) + abs(self.pos_north)
+
+
+
 if __name__ == "__main__":
-	f = Ferry()
+	f = Waypoint()
 	f.load("data.txt")
 	md = f.get_md()
-	print(f"Manhattan distance is {md}")
+	print(f"1: Manhattan distance is {md}")
+
+	f = Ship()
+	f.waypoint.pos_east = 10
+	f.waypoint.pos_north = 1
+	f.load("data.txt")
+	md = f.get_md()
+	print(f"2: Manhattan distance is {md}")