3

2022/03/README.md

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+# 03
+
+The first part is easily done by using the ascii number of the characters and 2 offsets. The second part I first though we need to find the groups on our own, but (RTFM...) it's just every 3 lines, so it's just a matter of using pythons `set`.
+
+<details>
+  <summary>Solutions</summary>
+  <ol>
+    <li>7746</li>
+    <li>2604</li>
+  </ol>
+</details>

2022/03/python/main.py

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+#!/usr/bin/env python
+
+from os.path import dirname, join
+
+# Day 03
+
+# Common
+
+
+def read_input(filename):
+    data = join(dirname(__file__), '..', filename)
+    with open(data) as f:
+        return f.read().strip()
+
+
+test = read_input('test.txt')
+data = read_input('input.txt')
+
+
+def score(char: str) -> int:
+    offset = 97-1 if char.islower() else 65-27
+    return ord(char) - offset
+
+
+class Rucksack:
+    def __init__(self, items: str):
+        self.l = len(items) // 2
+        self.items = items
+
+    def find_common(self) -> str:
+        front = self.items[:self.l]
+        back = self.items[self.l:]
+        intersection = set(front).intersection(set(back))
+        return list(intersection)[0]
+
+
+class Supplies:
+    def __init__(self, rucksacks: list[Rucksack]) -> None:
+        self.rucksacks = rucksacks
+
+    def get_common(self):
+        return sum([
+            score(rucksack.find_common())
+            for rucksack in self.rucksacks
+        ])
+
+    def groups(self):
+        group_size = 3
+        total = 0
+        for i in range(len(self.rucksacks)//group_size):
+            i *= group_size
+            subset = self.rucksacks[i:i+group_size]
+            sets = [set(rucksack.items) for rucksack in subset]
+            chars = sets[0]
+            for s in sets[1:]:
+                chars = chars.intersection(s)
+            total += score(list(chars)[0])
+        return total
+
+    @staticmethod
+    def parse(data: str):
+        rucksacks = [
+            Rucksack(item)
+            for item in data.split('\n')
+        ]
+        return Supplies(rucksacks)
+
+
+# 1
+print('1.')
+supplies = Supplies.parse(test)
+print(supplies.get_common())
+supplies = Supplies.parse(data)
+print(supplies.get_common())
+
+
+# 2
+print('\n2.')
+supplies = Supplies.parse(test)
+print(supplies.groups())
+supplies = Supplies.parse(data)
+print(supplies.groups())