[py] Solve 2024_04 part 1

py/aoc/__init__.py

@@ -2,7 +2,7 @@ import argparse
 import sys
 from pathlib import Path
 
-from . import y2015, y2016, y2017, y2018, y2020, y2021, y2022
+from . import y2015, y2016, y2017, y2018, y2020, y2021, y2022, y2024
 
 DAYS = {
     **y2015.DAYS,
@@ -12,6 +12,7 @@ DAYS = {
     **y2020.DAYS,
     **y2021.DAYS,
     **y2022.DAYS,
+    **y2024.DAYS,
 }
 
 

py/aoc/y2024/__init__.py

@@ -0,0 +1,5 @@
+from . import d04
+
+DAYS = {
+    "2024_04": d04.solve,
+}

py/aoc/y2024/d04.py

@@ -0,0 +1,31 @@
+def mirror_h(lines):
+    return [line[::-1] for line in lines]
+
+
+def mirror_v(lines):
+    return lines[::-1]
+
+
+def transpose(lines):
+    return ["".join(chars) for chars in zip(*lines)]
+
+
+def shift(lines):
+    return [" " * i + line + " " * (len(lines) - 1 - i) for i, line in enumerate(lines)]
+
+
+def count_xmas(lines):
+    return sum(line.count("XMAS") for line in lines)
+
+
+def solve(inputstr):
+    w2e = inputstr.strip().split()
+    n2s = transpose(w2e)
+    nw2se = transpose(mirror_v(shift(mirror_v(w2e))))
+    ne2sw = transpose(shift(w2e))
+
+    orientations = [w2e, n2s, nw2se, ne2sw]
+    orientations = orientations + [mirror_h(o) for o in orientations]
+
+    part1 = sum(count_xmas(o) for o in orientations)
+    print(f"Part 1: {part1}")