2015: d20: ex1: add solution

2015/d20/ex1/ex1.py

@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+
+import sys
+
+
+def solve(input: str) -> int:
+    needed = int(input.strip())
+    presents = [0] * (needed // 10)  # Surely this should be enough houses
+    for i in range(1, len(presents)):
+        for j in range(i, len(presents), i):
+            presents[j] += 10 * i
+    for i, total in enumerate(presents):
+        if total >= needed:
+            return i
+    assert False  # Sanity check
+
+
+def main() -> None:
+    input = sys.stdin.read()
+    print(solve(input))
+
+
+if __name__ == "__main__":
+    main()