Use python's cache decorator

day7/part2.py

@@ -1,25 +1,32 @@
 from pathlib import Path
+from functools import cache
 
 FILE = "input.txt"
 
+class Foo:
+    def __init__(self, grid: list[str]) -> None:
+        self.grid: list[str] = grid
+
+    def timelines(self) -> int:
+        start = self.grid[0].index('S')
+        return self.traverse(start, 1)
+
+    @cache
+    def traverse(self, position: int, level: int) -> int:
+        grid = self.grid[level:]
+        if not len(grid):
+            return 1
+        if grid[0][position] == '^':
+            return (
+                self.traverse(position-1, level + 1) +
+                self.traverse(position+1, level + 1)
+            )
+        return self.traverse(position, level + 1)
+
 def main():
     raw_lines = Path(FILE).read_text().splitlines()
-    position = raw_lines[0].index('S')
-    return traverse(position, raw_lines[1:], 0, dict())
+    return Foo(raw_lines).timelines()
 
-def traverse(position: int, grid: list[str], level: int, memo: dict[tuple[int, int], int]) -> int:
-    if (position, level) in memo.keys():
-        return memo[(position, level)]
-    if not len(grid):
-        return 1
-    if grid[0][position] == '^':
-        memo[(position, level)] = (
-            traverse(position-1, grid[1:], level+1, memo) +
-            traverse(position+1, grid[1:], level+1, memo)
-        )
-        return memo[(position, level)]
-    memo[(position, level)] = traverse(position, grid[1:], level+1, memo)
-    return memo[(position, level)]
 
 if __name__ == "__main__":
     print(main())