Advent of Code 2024 - Day 4 : Python version (#43)

Author: Allianzcortex

advent_of_code/2024(python)/day4.py

@@ -0,0 +1,55 @@
+
+prefix_dir = {
+    "up": [-1, 0],
+    "down": [1, 0],
+    "left": [0, -1],
+    "right": [0, 1],
+    "up-left": [-1, -1],
+    "up-right": [-1, 1],
+    "down-left": [1, -1],
+    "down-right": [1, 1],
+}
+
+def _solve_matrix_part1(matrix:list[str], target:str, x:int, y:int, dir:str) -> bool:
+
+    if x<0 or x>len(matrix)-1 or y<0 or y>len(matrix[0])-1:
+        return False
+    if matrix[x][y] != target[0]:
+        return False
+    if len(target) == 1:
+        return True
+    return _solve_matrix_part1(matrix,target[1:],x+prefix_dir[dir][0], y+prefix_dir[dir][1], dir)
+
+def solve_day4_part1(matrix:list[str]) -> int:
+
+    target = "XMAS"
+    res = 0
+    for i in range(len(matrix)):
+        for j in range(len(matrix[0])):
+            for dir in prefix_dir.keys():
+                res += int(_solve_matrix_part1(matrix, target, i, j, dir))
+    
+    return res
+
+def _solve_matrix_part2(matrix:list[str], x:int, y:int) -> bool:
+
+    if x+2>len(matrix)-1 or y+2>len(matrix[0])-1:
+        return False
+    x1_char = matrix[x][y] + matrix[x+1][y+1] + matrix[x+2][y+2]
+    x2_char = matrix[x][y+2] + matrix[x+1][y+1] + matrix[x+2][y]
+
+    targets = ("MAS", "SAM")
+    if x1_char in targets and x2_char in targets:
+        return True
+    
+    return False
+
+def solve_day4_part2(matrix:list[str]) -> int:
+
+    res = 0
+    for i in range(len(matrix)):
+        for j in range(len(matrix[0])):
+            res += _solve_matrix_part2(matrix, i, j)
+    return res
+
+

advent_of_code/2024(python)/test_day4.py

@@ -0,0 +1,30 @@
+import unittest
+
+from day4 import solve_day4_part1, solve_day4_part2
+
+
+matrix_day4 = [
+"MMMSXXMASM",
+"MSAMXMSMSA",
+"AMXSXMAAMM",
+"MSAMASMSMX",
+"XMASAMXAMM",
+"XXAMMXXAMA",
+"SMSMSASXSS",
+"SAXAMASAAA",
+"MAMMMXMMMM",
+"MXMXAXMASX",
+]
+
+
+
+class TestDay4(unittest.TestCase):
+
+    def test_part1(self):
+        self.assertEqual(solve_day4_part1(matrix_day4), 18)
+
+    def test_part2(self):
+        self.assertEqual(solve_day4_part2(matrix_day4), 9)
+
+if __name__ == "__main__":
+    unittest.main()