day04

1 files changed, 59 insertions, 0 deletions

diff --git a/2025/day04.py b/2025/day04.py
new file mode 100755
index 0000000..e69acd5
--- /dev/null
+++ b/2025/day04.py
@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+from functools import reduce
+from re import findall
+from copy import deepcopy
+import sys
+# import numpy as np
+
+filename = sys.argv[1] if len(sys.argv) == 2 \
+    else "in/" + sys.argv[0].split('/')[-1].rstrip(".py") + ".pzl"
+data = open(filename).read()
+lines = data.rstrip('\n').split('\n')
+
+res1 = 0
+res2 = 0
+
+D = dict()
+for x,line in enumerate(lines):
+    for y, c in enumerate(line):
+        D[(x,y)] = c
+
+for (x, y), c in D.items():
+    if c != '@':
+        continue
+    n = 0
+    for dx, dy in [(1, -1), (1, 0), (1, 1), (-1, -1),
+                   (-1, 0), (-1, 1), (0, -1), (0, 1)]:
+        nx = x + dx
+        ny = y + dy
+        if (nx, ny) in D and D[(nx, ny)] == '@':
+            n += 1
+    if n < 4:
+        res1 += 1
+
+def remove(D):
+    r = 0
+    for (x, y), c in D.items():
+        if c != '@':
+            continue
+        n = 0
+        for dx, dy in [(1, -1), (1, 0), (1, 1), (-1, -1),
+                       (-1, 0), (-1, 1), (0, -1), (0, 1)]:
+            nx = x + dx
+            ny = y + dy
+            if (nx, ny) in D and D[(nx, ny)] == '@':
+                n += 1
+        if n < 4:
+            r += 1
+            D[(x, y)] = '.'
+    return D, r
+
+D, r = remove(D)
+res2 += r
+while r > 0:
+    D, r = remove(D)
+    res2 += r
+
+print('res1:', res1)
+print('res2:', res2)
+