Day 20.

20.py

@@ -0,0 +1,11 @@
+from itertools import chain
+
+target = 34000000
+
+flatten = chain.from_iterable
+factors = lambda n: set(flatten((i, n//i) for i in range(1, int(n**0.5)+1) if n % i == 0))
+presents1 = lambda n: 10 * sum(x for x in factors(n))
+presents2 = lambda n: sum(11 * x for x in factors(n) if n // x <= 50)
+
+print(next(i for i in range(target) if presents1(i) > target))
+print(next(i for i in range(target) if presents2(i) > target))