From 99a7d62c30069a5ffe2210a72c7cf81e76a1f241 Mon Sep 17 00:00:00 2001
From: blenovo <bk@gmail.com>
Date: Wed, 16 Jul 2025 18:55:48 +0200
Subject: summertime warmup session with 2020 event

---
 2020/aoc2020-d09.py | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 2020/aoc2020-d09.py

(limited to '2020/aoc2020-d09.py')

diff --git a/2020/aoc2020-d09.py b/2020/aoc2020-d09.py
new file mode 100644
index 0000000..26c1c61
--- /dev/null
+++ b/2020/aoc2020-d09.py
@@ -0,0 +1,55 @@
+#advent of code 2020
+#day 09
+#genuinely surprised the simple solution worked
+#shamelessly googled the code for combinations, 
+#didn't feel like implementing it
+#if i reversed the "visited" list the runtime could be faster but w/e
+
+def PossibleCombs(n,k):
+	combinations = [];
+	if k==1: return n;
+	for i in range(len(n)):
+		head = n[i:i+1]
+		tail = PossibleCombs(n[i+1:],k-1);
+		for j in range(len(tail)):
+			if type(tail[j]) == int:
+				comb = head + [tail[j]]
+			else: 
+				comb = head + tail[j];
+			combinations.append(comb);
+	return combinations;
+
+p1 = None;
+limit = 25;
+numbers = [];
+PuzzleInput = open("09.in","r");
+for line in PuzzleInput: numbers.append(int(line));
+PuzzleInput.close();
+previous = numbers[:limit];
+counter = limit -1;
+
+for n in numbers[limit:]:
+	counter += 1;
+	found = False;
+	for combo in PossibleCombs(previous,2):
+		if n == sum(combo): 
+			previous = previous[1:] + [n];
+			found = True;
+			break;
+	if not found: 
+		p1 = n;
+		break;
+
+visited = numbers[:counter];
+for i,n in enumerate(visited):
+	subsum = 0 + n;
+	subcounter = 0 + i;
+	while subsum < p1:
+		subcounter += 1;
+		subsum += visited[subcounter];
+	if subsum == p1:
+		p2 = min(visited[i:subcounter]) + max(visited[i:subcounter]) ;
+		break;
+
+print("part 1 =",p1);
+print("part 2 =",p2);
-- 
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