From 838d06100b22de8e74bdb2a8d3e8d25d9f6c1559 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Engl=C3=B6f=20Ytterstr=C3=B6m?= <yttan@fastmail.se>
Date: Wed, 25 Oct 2023 23:27:51 +0200
Subject: [PATCH] Solve 2015:11 "Corporate Policy"

I brainfarted and had a hard time trying to
understand the instructions.

> Incrementing is just like counting with numbers: xx, xy, xz, ya, yb, and so on. Increase the rightmost letter one step; if it was z, it wraps around to a, and repeat with the next letter to the left until one doesn't wrap around.

I only managed to understand it by looking at solutions on the
subreddit, figuring out the correct behavior:

az -> ba, azzz -> baaa, azzzzz -> baaaaa etc.

I also sped up the test case containing `ghi` as initial password,
by looking for the leftmost invalid I, L or O and increase it,
replacing all following chars with `a`.

ghijklmn -> ghjaaaaa.
---
 2015-python/solutions/day_11.py  | 68 ++++++++++++++++++++++++++++++++
 2015-python/tests/test_day_11.py | 35 ++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 2015-python/solutions/day_11.py
 create mode 100644 2015-python/tests/test_day_11.py

diff --git a/2015-python/solutions/day_11.py b/2015-python/solutions/day_11.py
new file mode 100644
index 0000000..8bb0d8f
--- /dev/null
+++ b/2015-python/solutions/day_11.py
@@ -0,0 +1,68 @@
+import re
+from solutions import BaseSolution
+
+
+class Solution(BaseSolution):
+    input_file = "11.txt"
+
+    def __str__(self):
+        return "Day 11: Corporate Policy"
+
+    def is_valid(self, suggestion):
+        if "i" in suggestion or "l" in suggestion or "o" in suggestion:
+            return False
+        if (
+            len(
+                set(
+                    map(
+                        lambda x: x[0],
+                        filter(lambda x: x[0] == x[1], zip(suggestion, suggestion[1:])),
+                    )
+                )
+            )
+            < 2
+        ):
+            return False
+
+        def seq(abc):
+            a, b, c = abc
+            return ord(b) - ord(a) == 1 and ord(c) - ord(b) == 1
+
+        return any(map(seq, zip(suggestion, suggestion[1:], suggestion[2:])))
+
+    def parse_input(self, data):
+        return data
+
+    def solve(self, password):
+        def tick(p):
+            chars = list(p)[::-1]
+            i = 0
+            for c in chars:
+                if c == "z":
+                    chars[i] = "a"
+                else:
+                    chars[i] = chr(ord(chars[i]) + 1)
+                    break
+                i += 1
+            return "".join(chars[::-1])
+
+        unallowed = re.compile(r"i|l|o")
+        fastforward = re.search(unallowed, password)
+        if fastforward:
+            password = (
+                password[: fastforward.start()]
+                + chr(ord(password[fastforward.start()]) + 1)
+            ).ljust(len(password), "a")
+
+        while True:
+            password = tick(password)
+            if self.is_valid(password):
+                return password
+
+    def solve_again(self, puzzle_input):
+        return self.solve(self.solve(puzzle_input))
+
+
+if __name__ == "__main__":
+    solution = Solution()
+    solution.show_results()
diff --git a/2015-python/tests/test_day_11.py b/2015-python/tests/test_day_11.py
new file mode 100644
index 0000000..b1d148b
--- /dev/null
+++ b/2015-python/tests/test_day_11.py
@@ -0,0 +1,35 @@
+import unittest
+
+from solutions.day_11 import Solution
+
+
+class Day11TestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+        self.puzzle_input = self.solution.parse_input(
+            """
+        <REPLACE ME>
+        """
+        )
+
+    def test_parse_puzzle_input(self):
+        data = """
+        <REPLACE ME>
+        """.strip()
+        assert self.solution.parse_input(data) == "<REPLACE ME>"
+
+    def test_validate_passwords(self):
+        assert not self.solution.is_valid("hijklmmn")
+        assert not self.solution.is_valid("abbceffg")
+        assert not self.solution.is_valid("abbcegjk")
+
+    def test_solve_first_part(self):
+        assert self.solution.solve("abcdefgh") == "abcdffaa"
+        assert self.solution.solve("ghijklmn") == "ghjaabcc"
+
+    # def test_solve_second_part(self):
+    #     assert self.solution.solve_again(self.puzzle_input) == True
+
+
+if __name__ == "__main__":
+    unittest.main()