Day 11 - UGLY AF

day11/part1.py

@@ -0,0 +1,52 @@
+import numpy as np
+from numpy.lib.stride_tricks import as_strided
+
+from day11.common import char_to_int
+
+
+def get_filters(arr):
+    KERNEL_SHAPE = (3, 3)
+    return as_strided(
+        arr,
+        shape=(
+            arr.shape[0] - KERNEL_SHAPE[0] + 1,  # The feature map is a few pixels smaller than the input
+            arr.shape[1] - KERNEL_SHAPE[1] + 1,
+            KERNEL_SHAPE[0],
+            KERNEL_SHAPE[1],
+        ),
+        strides=(
+            arr.strides[0],
+            arr.strides[1],
+            arr.strides[0],  # When we move one step in the 3rd dimension, we should move one step in the original data too
+            arr.strides[1],
+        ),
+        writeable=False,  # totally use this to avoid writing to memory in weird places
+    )
+
+
+def parse(arr):
+    if arr[1, 1] == 0:
+        return 0
+    if np.count_nonzero(arr == 1) == 0:
+        return 1
+    if arr[1, 1] == 1 and np.count_nonzero(arr == 1) >= 5:
+        return -1
+    return arr[1, 1]
+
+
+lines = np.array([[char_to_int(x) for x in line.strip()] for line in open("input.txt")], dtype=np.byte)
+lines = np.pad(lines, 1, 'constant', constant_values=0)
+shape = np.array(lines.shape)
+last = -1
+while True:
+    curr = np.count_nonzero(lines == 1)
+    if curr == last:
+        print(last)
+        break
+    last = curr
+    expanded_input = get_filters(lines)
+    new_input = np.zeros(shape, dtype=np.byte)
+    for idx in np.ndindex(*shape-2):
+        target = tuple(np.array(idx) + 1)
+        new_input[target] = parse(expanded_input[idx])
+    lines = new_input