From f751b3b8d53d3a900a333a34a7313f2d26fa835e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Engl=C3=B6f=20Ytterstr=C3=B6m?= <yttan@fastmail.se>
Date: Wed, 4 Dec 2024 11:04:42 +0100
Subject: [PATCH] Solve 2024:4 p1-2 "Ceres Search"

Not gonna lie, This is not my gig skillwise. I had
much fun though!

A matrix would most likely make the code more
readable.

I relied massively on test cases here, so I share
them here instead of in the source code:

assert 1 == solve("""
    X.....
    .M....
    ..A...
    ...S..
    ..X...
    """.strip())[0]

    assert 2 == solve("""
    XS....
    .MA...
    ..AM..
    ...SX.
    ..X...
    """.strip())[0]

    assert 2 == solve("""
    ..S......
    ...A.....
    ....M....
    .....X...
    ..X...M..
    .......A.
    ........S
    """.strip())[0]

    assert 4 == solve("""
    X.SS
    M.AA
    A.MM
    S.XX
    ...M
    ...A
    ...S
    """.strip())[0]

    assert 4 == solve("""
    ...X...
    ...M...
    .X.A...
    XMASAMX
    .A.....
    .S.....
    """.strip())[0]

    assert 1 == solve("""
    ....X
    ...M.
    ..A..
    .S...
    """.strip())[0]

    assert 2 == solve("""
    ...SX
    ..AM.
    .MA..
    XS...
    """.strip())[0]

    assert 2 == solve("""
    ......X
    .....M.
    ....A..
    ...S...
    ..A....
    .M.....
    X......
    """.strip())[0]

    assert 1 == solve("""
    M.S
    .A.
    M.S
    """.strip())[1]

    assert 1 == solve("""
    M.M
    .A.
    S.S
    """.strip())[1]

    assert 1 == solve("""
    S.M
    .A.
    S.M
    """.strip())[1]

    assert 1 == solve("""
    S.S
    .A.
    M.M
    """.strip())[1]

    assert 1 == solve("""
    S.S
    .A.
    M.M
    """.strip())[1]

    assert 1 == solve("""
    .A.
    M.M
    .A.
    S.S
    """.strip())[1]

    assert 1 == solve("""
    M.M.
    .A.A
    S.S.
    """.strip())[1]

    assert 1 == solve("""
    M.M
    .A.
    S.S
    .A.
    """.strip())[1]

    assert 1 == solve("""
    .M.M
    A.A.
    .S.S
    """.strip())[1]
---
 2024-python/aoc.py           |  2 +-
 2024-python/output/day_04.py | 92 ++++++++++++++++++++++++++++++++++++
 2 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 2024-python/output/day_04.py

diff --git a/2024-python/aoc.py b/2024-python/aoc.py
index c84d089..8adeee7 100644
--- a/2024-python/aoc.py
+++ b/2024-python/aoc.py
@@ -4,7 +4,7 @@ from pathlib import Path
 
 def headline(n):
     """Print day number and name, followed by a ruler. Used by the answer decorator"""
-    print(f"\n--- Day {n} ---\n")
+    print(f"\nDay {int(n)} - https://adventofcode.com/{year}/day/{int(n)}\n")
 
 
 year = 2024
diff --git a/2024-python/output/day_04.py b/2024-python/output/day_04.py
new file mode 100644
index 0000000..17b6c84
--- /dev/null
+++ b/2024-python/output/day_04.py
@@ -0,0 +1,92 @@
+import re
+
+
+def solve(data):
+    row_count = len(data.split())
+    col_count = len(data.split()[0])
+    grid = [c for r in data.split() for c in r]
+    grid_rotated = [c for r in zip(*data.split()[::-1]) for c in r]
+    needle = r"(?=(XMAS|SAMX))"
+
+    p1 = len(re.findall(needle, data))
+    p1 += len(
+        re.findall(
+            needle,
+            "\n".join(["".join(r) for r in list(zip(*data.split()))]),
+        )
+    )
+
+    for cells, o in [
+        (grid, col_count),
+        (grid[::-1], col_count),
+        (grid_rotated, row_count),
+        (grid_rotated[::-1], row_count),
+    ]:
+        p1 += sum(
+            all(
+                [
+                    i % o < (o - 3),
+                    cells[i] == "X",
+                    cells[i + o + 1] == "M",
+                    cells[i + 2 * (o + 1)] == "A",
+                    cells[i + 3 * (o + 1)] == "S",
+                ]
+            )
+            for i in range(len(cells) - 3 * (o + 1))
+        )
+
+    p2 = sum(
+        [
+            1 <= (i % col_count) < col_count - 1
+            and grid[i] == "A"
+            and any(
+                [
+                    all(
+                        [
+                            grid[i - col_count - 1] == "M",
+                            grid[i - col_count + 1] == "M",
+                            grid[i + col_count - 1] == "S",
+                            grid[i + col_count + 1] == "S",
+                        ]
+                    ),
+                    all(
+                        [
+                            grid[i - col_count - 1] == "S",
+                            grid[i - col_count + 1] == "S",
+                            grid[i + col_count - 1] == "M",
+                            grid[i + col_count + 1] == "M",
+                        ]
+                    ),
+                    all(
+                        [
+                            grid[i - col_count - 1] == "M",
+                            grid[i - col_count + 1] == "S",
+                            grid[i + col_count - 1] == "M",
+                            grid[i + col_count + 1] == "S",
+                        ]
+                    ),
+                    all(
+                        [
+                            grid[i - col_count - 1] == "S",
+                            grid[i - col_count + 1] == "M",
+                            grid[i + col_count - 1] == "S",
+                            grid[i + col_count + 1] == "M",
+                        ]
+                    ),
+                ]
+            )
+            for i in range(col_count + 1, len(grid) - col_count - 1)
+        ]
+    )
+
+    return p1, p2
+
+
+if __name__ == "__main__":
+    with open("./input/04.txt", "r") as f:
+        inp = f.read().strip()
+
+    p1, p2 = solve(inp)
+
+    print(p1)
+    print(p2)