Advent of Code 2025 - Day 5 : Python version

advent_of_code/2025(python)/day4.py

@@ -0,0 +1,61 @@
+
+dirs = [
+    [-1, -1],
+    [-1, 0],
+    [-1, 1],
+    [0, -1],
+    [0, 1],
+    [1, -1],
+    [1, 0],
+    [1, 1]
+]
+
+
+def solve_day4_part1(grid):
+    res = 0
+    row, column = len(grid), len(grid[0])
+
+    for i in range(row):
+        for j in range(column):
+            if grid[i][j] == '.':
+                continue
+            roll_cnt = 0
+            for dir in dirs:
+                x, y = i+dir[0], j+dir[1]
+                if x < 0 or x > row-1 or y < 0 or y > column-1:
+                    continue
+                if grid[x][y] == '@':
+                    roll_cnt += 1
+
+            if roll_cnt < 4:
+                res += 1
+
+    return res
+
+
+def solve_day4_part2(grid):
+    res = 0
+    row, column = len(grid), len(grid[0])
+
+    while True:
+        is_roll_moved = False
+        for i in range(row):
+            for j in range(column):
+                if grid[i][j] == '.':
+                    continue
+                roll_cnt = 0
+                for dir in dirs:
+                    x, y = i+dir[0], j+dir[1]
+                    if x < 0 or x > row-1 or y < 0 or y > column-1:
+                        continue
+                    if grid[x][y] == '@':
+                        roll_cnt += 1
+
+                if roll_cnt < 4:
+                    is_roll_moved = True
+                    grid[i] = grid[i][:j]+'.'+grid[i][j+1:]
+                    res += 1
+
+        if not is_roll_moved:
+            break
+    return res

advent_of_code/2025(python)/test_day4.py

@@ -0,0 +1,29 @@
+import unittest
+
+from day4 import solve_day4_part1, solve_day4_part2
+
+question_input = [
+    "..@@.@@@@.",
+    "@@@.@.@.@@",
+    "@@@@@.@.@@",
+    "@.@@@@..@.",
+    "@@.@@@@.@@",
+    ".@@@@@@@.@",
+    ".@.@.@.@@@",
+    "@.@@@.@@@@",
+    ".@@@@@@@@.",
+    "@.@.@@@.@.",
+]
+
+
+class TestSample(unittest.TestCase):
+
+    def test_part1(self):
+        self.assertEqual(solve_day4_part1(question_input), 13)
+
+    def test_part2(self):
+        self.assertEqual(solve_day4_part2(question_input), 43)
+
+
+if __name__ == "__main__":
+    unittest.main()