2015 day 20.

src/holt59/aoc/2015/day20.py

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+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}")

src/holt59/aoc/inputs/holt59/2015/day20.txt

@@ -0,0 +1 @@
+34000000