From a34941dbd92cdf3d319cb8f7c66e3d72801cf3b7 Mon Sep 17 00:00:00 2001
From: Bruno BELANYI <bruno@belanyi.fr>
Date: Sun, 13 Dec 2020 07:38:51 +0100
Subject: [PATCH] 2020: d13: ex1: add solution

---
 2020/d13/ex1/ex1.py | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100755 2020/d13/ex1/ex1.py

diff --git a/2020/d13/ex1/ex1.py b/2020/d13/ex1/ex1.py
new file mode 100755
index 0000000..fadaefb
--- /dev/null
+++ b/2020/d13/ex1/ex1.py
@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+
+import itertools
+import math
+import sys
+from typing import List, Tuple
+
+
+def find_first_factor(earliest: int, timings: List[int]) -> Tuple[int, int]:
+    timings = sorted(timings)
+    for t in itertools.count(earliest):
+        for n in timings:
+            if t % n == 0:
+                return t - earliest, n
+
+    assert False  # Make Mypy happy
+
+
+def solve(raw: List[str]) -> int:
+    return math.prod(
+        find_first_factor(int(raw[0]), [int(i) for i in raw[1].split(",") if i != "x"])
+    )
+
+
+def main() -> None:
+    input = [line.strip() for line in sys.stdin.readlines()]
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()