From 2597235d0ce52ff9d2542ae2f94752b0c185b8e5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mika=C3=ABl=20Capelle?= <capelle.mikael@gmail.com>
Date: Sat, 6 Jan 2024 22:07:34 +0100
Subject: [PATCH] 2015 day 20.

---
 src/holt59/aoc/2015/day20.py                | 28 +++++++++++++++++++++
 src/holt59/aoc/inputs/holt59/2015/day20.txt |  1 +
 2 files changed, 29 insertions(+)
 create mode 100644 src/holt59/aoc/2015/day20.py
 create mode 100644 src/holt59/aoc/inputs/holt59/2015/day20.txt

diff --git a/src/holt59/aoc/2015/day20.py b/src/holt59/aoc/2015/day20.py
new file mode 100644
index 0000000..4eb3f71
--- /dev/null
+++ b/src/holt59/aoc/2015/day20.py
@@ -0,0 +1,28 @@
+import itertools
+import sys
+
+target = int(sys.stdin.read())
+
+
+def presents(n: int, elf: int, max: int = target) -> int:
+    count = 0
+    k = 1
+    while k * k < n:
+        if n % k == 0:
+            if n // k <= max:
+                count += elf * k
+            if k <= max:
+                count += elf * (n // k)
+        k += 1
+
+    if k * k == n and k <= max:
+        count += elf * k
+
+    return count
+
+
+answer_1 = next(n for n in itertools.count(1) if presents(n, 10) >= target)
+print(f"answer 1 is {answer_1}")
+
+answer_2 = next(n for n in itertools.count(1) if presents(n, 11, 50) >= target)
+print(f"answer 2 is {answer_2}")
diff --git a/src/holt59/aoc/inputs/holt59/2015/day20.txt b/src/holt59/aoc/inputs/holt59/2015/day20.txt
new file mode 100644
index 0000000..c519ba7
--- /dev/null
+++ b/src/holt59/aoc/inputs/holt59/2015/day20.txt
@@ -0,0 +1 @@
+34000000