From 37aa8eec0498d7e8491084711132f16db9129a39 Mon Sep 17 00:00:00 2001
From: Tom van der Lee <tom@ScaryTerry.local>
Date: Tue, 15 Dec 2020 13:14:58 +0100
Subject: Added day 9

---
 day9/__init__.py | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 day9/__init__.py

(limited to 'day9/__init__.py')

diff --git a/day9/__init__.py b/day9/__init__.py
new file mode 100644
index 0000000..0cf3770
--- /dev/null
+++ b/day9/__init__.py
@@ -0,0 +1,63 @@
+from typing import Any, Iterator, List
+
+from aoc import BaseAssignment
+
+
+class Assignment(BaseAssignment):
+    def __init__(self, path, preamble_length=25):
+        super().__init__(path)
+        self.preamble_length = int(preamble_length)
+
+    def read_input(self, example=False) -> List:
+        return list(super(Assignment, self).read_input(example))
+
+    def parse_item(self, item: str) -> Any:
+        return int(item)
+
+
+class AssignmentOne(Assignment):
+    def find_invalid(self, input: List, preamble_length: int = 25) -> int:
+        preamble = sorted(input[:preamble_length])
+        to_check = input[preamble_length]
+
+        front_position = 0
+        end_position = preamble_length - 1
+
+        while True:
+            if front_position is end_position:
+                return to_check
+
+            sum = preamble[front_position] + preamble[end_position]
+
+            if sum > to_check:
+                end_position -= 1
+            elif sum < to_check:
+                front_position += 1
+            else:
+                break
+
+        return self.find_invalid(input[1:], preamble_length=preamble_length)
+
+    def run(self, input: List) -> int:
+        return self.find_invalid(
+            input, preamble_length=int(self.preamble_length))
+
+
+class AssignmentTwo(AssignmentOne):
+    def find_weakness(self, input: List, invalid_nr: int) -> int:
+        for index, current_num in enumerate(input):
+            if index < 2:
+                continue
+
+            items_to_check = input[:index]
+            sum_list = sum(items_to_check)
+
+            if sum_list > invalid_nr:
+                break
+            elif sum_list == invalid_nr:
+                return min(items_to_check) + max(items_to_check)
+
+        return self.find_weakness(input[1:], invalid_nr)
+
+    def run(self, input: List) -> int:
+        return self.find_weakness(input, super().run(input))
-- 
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