From 03abb1a5ae384dd8ae4ffa17f03941ceef2cf995 Mon Sep 17 00:00:00 2001
From: Xiretza <xiretza@xiretza.xyz>
Date: Tue, 1 Dec 2020 16:50:45 +0100
Subject: [PATCH] day1: modify python for part2

---
 2020/day1/day1.py | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/2020/day1/day1.py b/2020/day1/day1.py
index 8371aee..b7a8f39 100755
--- a/2020/day1/day1.py
+++ b/2020/day1/day1.py
@@ -1,15 +1,22 @@
 #!/usr/bin/env python
+import itertools
 import sys
 from typing import Iterable
 
-def find2020(nums: Iterable[int]) -> int:
-    candidates = set()
+def product(nums: Iterable[int]) -> int:
+    """
+    Returns the product of all elements in 'nums'
+    """
+    x = 1
     for num in nums:
-        opposite = 2020-num
-        if num in candidates:
-            return num * opposite
-        candidates.add(opposite)
+        x *= num
+    return x
+
+def find_summing(arity: int, nums: Iterable[int]) -> int:
+    return product(next(filter(lambda xs: sum(xs) == 2020, itertools.permutations(nums, r=arity))))
 
 if __name__ == '__main__':
     with open(sys.argv[1], 'r') as f:
-        print(find2020(int(n) for n in f.readlines()))
+        nums = [int(n) for n in f.readlines()]
+    print(find_summing(2, nums))
+    print(find_summing(3, nums))