2024 day 4

aoc_cas/aoc2024/day4.py

@@ -0,0 +1,75 @@
+from aoc_cas.util import solve_with_data
+
+UP = (-1, 0)
+DOWN = (1, 0)
+LEFT = (0, -1)
+RIGHT = (0, 1)
+NE = (-1, 1)
+NW = (-1, -1)
+SE = (1, 1)
+SW = (1, -1)
+
+
+def _count_xmas(grid: list[list[str]], y: int, x: int) -> int:
+    M, N = len(grid), len(grid[0])
+    word_to_find = "XMAS"
+    word_count = 0
+    for dy, dx in [UP, DOWN, LEFT, RIGHT, NE, NW, SE, SW]:
+        for i, c in enumerate(word_to_find):
+            yy, xx = y + dy * i, x + dx * i
+            if not (0 <= yy < M and 0 <= xx < N) or grid[yy][xx] != c:
+                break
+        else:
+            word_count += 1
+    return word_count
+
+
+def _parse_data(data: str) -> list[list[str]]:
+    return [list(line) for line in data.splitlines()]
+
+
+def part_a(data: str) -> int:
+    grid = _parse_data(data)
+    M, N = len(grid), len(grid[0])
+    xmas_count = 0
+    for y in range(M):
+        for x in range(N):
+            xmas_count += _count_xmas(grid, y, x)
+    return xmas_count
+
+
+def _is_mas_x(grid: list[list[str]], y: int, x: int) -> bool:
+    M, N = len(grid), len(grid[0])
+    if not (1 <= y < M - 1 and 1 <= x < N - 1):
+        # OOB
+        return False
+    # Build a string of the current cell and its diagonal neighbors
+    # 5.2
+    # .1.
+    # 4.3
+    coords = ((y + dy, x + dx) for dy, dx in [(0, 0), NE, SE, SW, NW])
+    x_string = "".join(grid[yy][xx] for yy, xx in coords)
+    # Check if the string is is a MAS X
+    return x_string in {"AMMSS", "ASSMM", "AMSSM", "ASMMS"}
+
+
+def part_b(data: str) -> int:
+    grid = _parse_data(data)
+    M, N = len(grid), len(grid[0])
+    return sum(_is_mas_x(grid, y, x) for y in range(M) for x in range(N))
+
+
+if __name__ == "__main__":
+    data = """
+MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX
+""".strip()
+    solve_with_data(2024, 4, data, answer_a=18, answer_b=9)

aoc_cas/util.py

@@ -9,17 +9,22 @@ def load_module(year: int, day: int):
 
 
 def solve_with_examples(year: int, day: int) -> None:
-    mod = load_module(year, day)
     puzzle = Puzzle(year, day)
     print(f"Testing example data")
+
     puzzle.prose0_path.unlink(missing_ok=True)
     for example in puzzle.examples:
-        print(f"\n{example.input_data}\n")
-        if example.answer_a is not None:
-            part_a_result = str(mod.part_a(example.input_data))
-            correct = part_a_result == example.answer_a
-            print(f"{'❌✅'[correct]} [Part A] Actual: {part_a_result} - Expected: {example.answer_a}")
-        if example.answer_b is not None:
-            part_b_result = str(mod.part_b(example.input_data))
-            correct = part_b_result == example.answer_b
-            print(f"{'❌✅'[correct]} [Part B] Actual: {part_b_result} - Expected: {example.answer_b}\n")
+        solve_with_data(year, day, example.input_data, answer_a=example.answer_a, answer_b=example.answer_b)
+
+
+def solve_with_data(year: int, day: int, input_data: str, *, answer_a: object, answer_b: object = None) -> None:
+    mod = load_module(year, day)
+    print(f"\n{input_data}\n")
+    if answer_a is not None:
+        part_a_result = str(mod.part_a(input_data))
+        correct = part_a_result == str(answer_a)
+        print(f"{'❌✅'[correct]} [Part A] Actual: {part_a_result} - Expected: {answer_a}")
+    if answer_b is not None:
+        part_b_result = str(mod.part_b(input_data))
+        correct = part_b_result == str(answer_b)
+        print(f"{'❌✅'[correct]} [Part B] Actual: {part_b_result} - Expected: {answer_b}\n")

precommit

@@ -0,0 +1,4 @@
+#!/bin/bash
+set -euo pipefail
+echo "Black formatting"
+poetry run black . --check

tests/fixtures/2024/4.txt

@@ -0,0 +1,12 @@
+MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX
+18
+9