2025(04): fix part 1

That was harder than it should have been.

2025/04/README.md

@@ -47,3 +47,136 @@ In this example, there are _`13`_ rolls of paper that can be accessed by a forkl
     
 
 Consider your complete diagram of the paper roll locations. _How many rolls of paper can be accessed by a forklift?_
+
+### Part Two
+
+Now, the Elves just need help accessing as much of the paper as they can.
+
+Once a roll of paper can be accessed by a forklift, it can be _removed_. Once a roll of paper is removed, the forklifts might be able to access _more_ rolls of paper, which they might also be able to remove. How many total rolls of paper could the Elves remove if they keep repeating this process?
+
+Starting with the same example as above, here is one way you could remove as many rolls of paper as possible, using highlighted _`@`_ to indicate that a roll of paper is about to be removed, and using `x` to indicate that a roll of paper was just removed:
+
+    Initial state:
+    ..@@.@@@@.
+    @@@.@.@.@@
+    @@@@@.@.@@
+    @.@@@@..@.
+    @@.@@@@.@@
+    .@@@@@@@.@
+    .@.@.@.@@@
+    @.@@@.@@@@
+    .@@@@@@@@.
+    @.@.@@@.@.
+    
+    Remove 13 rolls of paper:
+    ..xx.xx@x.
+    x@@.@.@.@@
+    @@@@@.x.@@
+    @.@@@@..@.
+    x@.@@@@.@x
+    .@@@@@@@.@
+    .@.@.@.@@@
+    x.@@@.@@@@
+    .@@@@@@@@.
+    x.x.@@@.x.
+    
+    Remove 12 rolls of paper:
+    .......x..
+    .@@.x.x.@x
+    x@@@@...@@
+    x.@@@@..x.
+    .@.@@@@.x.
+    .x@@@@@@.x
+    .x.@.@.@@@
+    ..@@@.@@@@
+    .x@@@@@@@.
+    ....@@@...
+    
+    Remove 7 rolls of paper:
+    ..........
+    .x@.....x.
+    .@@@@...xx
+    ..@@@@....
+    .x.@@@@...
+    ..@@@@@@..
+    ...@.@.@@x
+    ..@@@.@@@@
+    ..x@@@@@@.
+    ....@@@...
+    
+    Remove 5 rolls of paper:
+    ..........
+    ..x.......
+    .x@@@.....
+    ..@@@@....
+    ...@@@@...
+    ..x@@@@@..
+    ...@.@.@@.
+    ..x@@.@@@x
+    ...@@@@@@.
+    ....@@@...
+    
+    Remove 2 rolls of paper:
+    ..........
+    ..........
+    ..x@@.....
+    ..@@@@....
+    ...@@@@...
+    ...@@@@@..
+    ...@.@.@@.
+    ...@@.@@@.
+    ...@@@@@x.
+    ....@@@...
+    
+    Remove 1 roll of paper:
+    ..........
+    ..........
+    ...@@.....
+    ..x@@@....
+    ...@@@@...
+    ...@@@@@..
+    ...@.@.@@.
+    ...@@.@@@.
+    ...@@@@@..
+    ....@@@...
+    
+    Remove 1 roll of paper:
+    ..........
+    ..........
+    ...x@.....
+    ...@@@....
+    ...@@@@...
+    ...@@@@@..
+    ...@.@.@@.
+    ...@@.@@@.
+    ...@@@@@..
+    ....@@@...
+    
+    Remove 1 roll of paper:
+    ..........
+    ..........
+    ....x.....
+    ...@@@....
+    ...@@@@...
+    ...@@@@@..
+    ...@.@.@@.
+    ...@@.@@@.
+    ...@@@@@..
+    ....@@@...
+    
+    Remove 1 roll of paper:
+    ..........
+    ..........
+    ..........
+    ...x@@....
+    ...@@@@...
+    ...@@@@@..
+    ...@.@.@@.
+    ...@@.@@@.
+    ...@@@@@..
+    ....@@@...
+    
+
+Stop once no more rolls of paper are accessible by a forklift. In this example, a total of _`43`_ rolls of paper can be removed.
+
+Start with your original diagram. _How many rolls of paper in total can be removed by the Elves and their forklifts?_

2025/04/part1.py

@@ -32,15 +32,18 @@ def count_neighbours(tp_map):
 	for x, y in np.ndindex(tp_map.shape):
 		if not tp_map[x,y]:
 			continue
+		L_x, L_y = tp_map.shape
 		dX, dY = X.copy() + x, Y.copy() + y
-		legal_idx = (dX >= 0)*(dX < X.shape[0])*(dY >= 0)*(dY < Y.shape[1])
+		legal_idx = (dX >= 0)*(dX < L_x)*(dY >= 0)*(dY < L_y)*((dX != x)|(dY != y))
 		neighbour_counts[x, y] = (tp_map[dX[legal_idx], dY[legal_idx]]).sum()
-	print(neighbour_counts)
 	max_rolls = 4
-	print(neighbour_counts < max_rolls)
+	return (neighbour_counts[tp_map] < max_rolls).sum()
-	return (neighbour_counts < max_rolls).sum()
 
 if __name__ == "__main__":
 	test_map = read_map("testinput")
-	print(test_map)
+	# print(test_map)
-	print(count_neighbours(test_map))
+	assert count_neighbours(test_map) == 13
+	# TODO: Compare the output map.
+
+	real_map = read_map("input")
+	print(count_neighbours(real_map))

2025/04/testoutput

@@ -0,0 +1,10 @@
+..xx.xx@x.
+x@@.@.@.@@
+@@@@@.x.@@
+@.@@@@..@.
+x@.@@@@.@x
+.@@@@@@@.@
+.@.@.@.@@@
+x.@@@.@@@@
+.@@@@@@@@.
+x.x.@@@.x.