move to 2020 fodler

2020/solutions/6/README.md

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+# 6
+
+Basically I own this one to the built in `set()` of python.
+
+The first is an union, the second an intersection. Did not know they existed
+
+<details>
+  <summary>Solutions</summary>
+  <ol>
+    <li>6809</li>
+    <li>3394</li>
+  </ol>
+</details>

2020/solutions/6/python/main.py

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+from os.path import join, dirname
+from itertools import product
+from typing import List, Set, Tuple
+from functools import reduce
+
+
+data = join(dirname(__file__), '../data.txt')
+with open(data) as f:
+    groups = f.read().strip().split('\n\n')
+
+    at_least_one: List[int] = []
+    everyone: List[int] = []
+    for group in groups:
+        answers: Set[str] = set()
+        combined = None
+        for answer in group.split('\n'):
+            answer = answer.strip()
+            as_set = set(list(answer))
+            answers = answers.union(as_set)
+            combined = as_set if combined == None else combined.intersection(
+                as_set)
+        at_least_one.append(len(answers))
+        everyone.append(len(combined))
+        # print(single)
+        # print(reduce(lambda a, b: a.intersection(b), single))
+
+    print(f'At least one person: {sum(at_least_one)}')
+    print(f'Everyone: {sum(everyone)}')