2024(6): add verbose bool and write idea for part two out

2024/06/part1.py

@@ -2,12 +2,7 @@ import numpy as np
 from enum import Enum
 
 
-'''
+verbose = False
-idee:
-	sla ook het kleine voorbeeld op
-	guard_directions = ["^", ">", "v", "<"]
-	guard_path = [] # list of tuples (x, y)
-'''
 
 class Map:
 	directions = ["^", ">", "v", "<"]
@@ -30,20 +25,25 @@ class Map:
 		"""
 
 		next_pos = tuple([self.pos[i] + self.step_per_direction[self.directions.index(self.direction)][i] for i in range(len(self.pos))])
-		print("next_pos", next_pos)
+		if verbose:
+			print("next_pos", next_pos)
 		return next_pos
 
 	def pos_in_map(self, pos):
 		"""
 		Returns whether pos is in the map.
 		"""
-		print("pos_in_map", pos) 
+
+		if verbose:
+			print("pos_in_map", pos) 
 		return pos[0] >= 0 and pos[0] < self.map.shape[0] \
 		   and pos[1] >= 0 and pos[0] < self.map.shape[1]
 
 	def look_ahead(self):
 		next_step = self.next_pos()
-		print("look_ahead.next_step", next_step)
+		if verbose:
+			print("look_ahead.next_step", next_step)
+
 		if not self.pos_in_map(next_step):
 			return self.Tiles.BORDER
 		if self.map[*next_step] == "#":
@@ -89,10 +89,11 @@ class Map:
 
 		# Find the location of the guard in the map.
 		guards = self.seek_guard_in_map()
-		print(guards)
+
+		if verbose:
+			print(guards)
 		assert len(guards) == 1, "There should only be one guard in the map."
 
-		print(guards)
 		self.pos = guards[0]
 		self.trace.append(self.pos)
 		self.direction = m.map[self.pos]
@@ -106,9 +107,11 @@ class Map:
 		"""
 
 		next_tile = self.look_ahead()
-		print("step.next_tile", next_tile)
+		if verbose:
+			print("step.next_tile", next_tile)
 
 		if next_tile == self.Tiles.FREE:
+			# TODO: Really take a step! Do not only turn.
 			self.pos = self.next_pos()
 			self.trace.append(self.pos)
 			return True
@@ -137,7 +140,8 @@ if __name__ == "__main__":
 	m.load_map("input")
 
 	while m.step():
-		print(m.pos, m.direction)
+		if verbose:
+			print(m.pos, m.direction)
 		#m.show()
-	print(len(m.trace), m.trace)
+	#print(len(m.trace), m.trace)
 	print(len(set(m.trace)))

2024/06/part2.py

@@ -0,0 +1,28 @@
+from part1 import *
+
+thoughts = \
+"""
+So, we can place an obstacle on each of the 130*130 - #obstacles = 16900
+- obstacles positions, but the initial path only covers 1512 positions
+(thus 1512 - 1 = 1511 steps). By instead placing an obstacle on each of
+those steps, we can find a loop.
+
+The other thing we need to do, is detect loops. For that, It would be
+nice to store both positions and directions to establish uniqueness,
+or just check whether it is the fifth time in a position (as we have
+then travelled to that position at least twice from at least one
+position; see Pigeonhole principle).
+"""
+
+if __name__ == "__main__":
+	m = Map()
+	#m.load_map("testinput")
+	m.load_map("input")
+
+	while m.step():
+		# After each step, we can fork the map and add the obstacle.
+		print(m.pos, m.direction)
+
+		#m.show()
+	print(len(m.trace), m.trace)
+	print(len(set(m.trace)))