2024(6): attempt to troubleshoot slowness

It takes 10 - 20 minutes to solve it. It is too slow. It seems that
List.count takes too long.

2024/06/part2.py

@@ -1,5 +1,8 @@
 from part1 import *
 
+
+verbose = False
+
 thoughts = \
 """
 So, we can place an obstacle on each of the 130*130 - #obstacles = 16900
@@ -18,15 +21,32 @@ if __name__ == "__main__":
 	m = Map()
 	#m.load_map("testinput")
 	m.load_map("input")
+
+	# Prepare forked map for speed
+	forked_map = m.copy()
+	#forked_map = Map()
+	#forked_map.load_map("input")
+	begin_pos = m.pos
+	begin_direction = m.direction
+
 	loop_obstacles = []
+	i = 0
 
 	while m.step():
+		print(i)
 		if verbose:
 			print(m.pos, m.direction)
 
 		# Create a copy
-		forked_map = m.copy()
+		#forked_map = m.copy()
-		forked_map.map[forked_map.next_pos()] = Map.Tiles.OBSTACLE.value
+		#forked_map = Map()
+		#forked_map.load_map("input")
+		#forked_map.map = m.map.copy()
+		forked_map.map[m.next_pos()] = Map.Tiles.OBSTACLE.value
+		forked_map.map[m.pos] = m.map[m.pos]
+		forked_map.pos = begin_pos
+		forked_map.direction = begin_direction
+		forked_map.trace = [begin_pos]
 		print(f"Forking at {forked_map.next_pos()}... ", end="")
 		try:
 			while forked_map.step():
@@ -36,6 +56,9 @@ if __name__ == "__main__":
 			loop_obstacles.append(m.next_pos())
 		else:
 			print("no loop.")
+		i += 1
+		if i > 100:
+			break
 		#m.show()
 	#print(len(m.trace), m.trace)
 	#print(len(set(m.trace)))