AoC 2025 Day 7

Author: pareronia

README.md

@@ -2,13 +2,13 @@
 
 ## 2025
 
-![](https://img.shields.io/badge/stars%20⭐-13-yellow)
-![](https://img.shields.io/badge/days%20completed-6-red)
+![](https://img.shields.io/badge/stars%20⭐-14-yellow)
+![](https://img.shields.io/badge/days%20completed-7-red)
 
 <!-- @BEGIN:ImplementationsTable:2025@ -->
 | | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
-| python3 | [✓](src/main/python/AoC2025_01.py) | [✓](src/main/python/AoC2025_02.py) | [✓](src/main/python/AoC2025_03.py) | [✓](src/main/python/AoC2025_04.py) | [✓](src/main/python/AoC2025_05.py) | [✓](src/main/python/AoC2025_06.py) |  |  |  |  |  |  |
+| python3 | [✓](src/main/python/AoC2025_01.py) | [✓](src/main/python/AoC2025_02.py) | [✓](src/main/python/AoC2025_03.py) | [✓](src/main/python/AoC2025_04.py) | [✓](src/main/python/AoC2025_05.py) | [✓](src/main/python/AoC2025_06.py) | [✓](src/main/python/AoC2025_07.py) |  |  |  |  |  |
 | java | [✓](src/main/java/AoC2025_01.java) | [✓](src/main/java/AoC2025_02.java) | [✓](src/main/java/AoC2025_03.java) | [✓](src/main/java/AoC2025_04.java) | [✓](src/main/java/AoC2025_05.java) | [✓](src/main/java/AoC2025_06.java) |  |  |  |  |  |  |
 | bash | [✓](src/main/bash/AoC2025_01.sh) | [✓](src/main/bash/AoC2025_02.sh) | [✓](src/main/bash/AoC2025_03.sh) | [✓](src/main/bash/AoC2025_04.sh) | [✓](src/main/bash/AoC2025_05.sh) | [✓](src/main/bash/AoC2025_06.sh) |  |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2025@ -->

src/main/python/AoC2025_07.py

@@ -0,0 +1,99 @@
+#! /usr/bin/env python3
+#
+# Advent of Code 2025 Day 7
+#
+
+import sys
+from functools import cache
+
+from aoc.common import InputData
+from aoc.common import SolutionBase
+from aoc.common import aoc_samples
+from aoc.geometry import Direction
+from aoc.grid import Cell
+from aoc.grid import CharGrid
+
+Input = InputData
+Output1 = int
+Output2 = int
+
+
+TEST = """\
+.......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+...............
+"""
+
+
+class Solution(SolutionBase[Input, Output1, Output2]):
+    def parse_input(self, input_data: InputData) -> Input:
+        return input_data
+
+    def part_1(self, inputs: Input) -> Output1:
+        grid = CharGrid.from_strings(list(inputs))
+        beams = {next(grid.get_all_equal_to("S")).col}
+        ans = 0
+        for sp in grid.get_all_equal_to("^"):
+            if sp.col in beams:
+                ans += 1
+                beams.remove(sp.col)
+                for d in (Direction.LEFT, Direction.RIGHT):
+                    beams.add(sp.at(d).col)
+        return ans
+
+    def part_2(self, inputs: Input) -> Output2:
+        grid = CharGrid.from_strings(list(inputs))
+        start = next(grid.get_all_equal_to("^"))
+        splitters = set(grid.get_all_equal_to("^")) | {start}
+
+        @cache
+        def dfs(cell: Cell) -> int:
+            if cell == start:
+                return 1
+            ans = 0
+            for n in grid.get_cells_n(cell):
+                if n in splitters:
+                    break
+                for d in (Direction.LEFT, Direction.RIGHT):
+                    nxt = n.at(d)
+                    if nxt in splitters:
+                        ans += dfs(nxt)
+            return ans
+
+        bottom_left = Cell(grid.get_max_row_index(), 0)
+        return dfs(bottom_left) + sum(
+            dfs(cell) for cell in grid.get_cells_e(bottom_left)
+        )
+
+    @aoc_samples(
+        (
+            ("part_1", TEST, 21),
+            ("part_2", TEST, 40),
+        )
+    )
+    def samples(self) -> None:
+        pass
+
+
+solution = Solution(2025, 7)
+
+
+def main() -> None:
+    solution.run(sys.argv)
+
+
+if __name__ == "__main__":
+    main()