2017: d13: ex1: add solution

2017/d13/ex1/ex1.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+
+import sys
+
+
+def solve(input: str) -> int:
+    def parse(input: str) -> dict[int, int]:
+        return {
+            depth: range
+            for depth, range in (map(int, l.split(": ")) for l in input.splitlines())
+        }
+
+    def would_catch(depth: int, range: int) -> bool:
+        cycle_length = (range - 1) * 2
+        return depth % cycle_length == 0
+
+    def compute_severity(firewall: dict[int, int]) -> int:
+        return sum(
+            depth * range
+            for depth, range in firewall.items()
+            if would_catch(depth, range)
+        )
+
+    firewall = parse(input)
+    return compute_severity(firewall)
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()