From f82b6cd9b55c79e44a5811868335b6cecb05d12d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Ytterstr=C3=B6m?= <yttan@fastmail.se>
Date: Sun, 5 Dec 2021 08:30:54 +0100
Subject: [PATCH] Solve 2021:5 "Hydrothermal Venture"

Tricky part, got the test data correct at part 1 long before the actual input gace the correct answers. Pure luck I guess.

Part 2 I got stuck on, and resolved to visualization by a loop of
prints.
---
 2021-python/solutions/day_05.py  | 55 ++++++++++++++++++++++++++++++++
 2021-python/tests/test_day_05.py | 39 ++++++++++++++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 2021-python/solutions/day_05.py
 create mode 100644 2021-python/tests/test_day_05.py

diff --git a/2021-python/solutions/day_05.py b/2021-python/solutions/day_05.py
new file mode 100644
index 0000000..28c95a2
--- /dev/null
+++ b/2021-python/solutions/day_05.py
@@ -0,0 +1,55 @@
+import re
+from itertools import chain
+from collections import defaultdict
+from solutions import BaseSolution
+
+
+class Solution(BaseSolution):
+    input_file = "05.txt"
+
+    def __str__(self):
+        return "Day 5: Hydrothermal Venture"
+
+    def parse_input(self, data):
+        return list(
+            map(
+                lambda s: tuple(map(int, re.findall(r"\d+", s))),
+                data.strip().splitlines(),
+            )
+        )
+
+    def solve(self, puzzle_input):
+        hv = list(filter(lambda l: l[0] == l[2] or l[1] == l[3], puzzle_input))
+        return self._overlaps(hv)
+
+    def solve_again(self, puzzle_input):
+        hvd = list(
+            filter(
+                lambda l: l[0] == l[2] or l[1] == l[3] or self._diagonal(*l),
+                puzzle_input,
+            )
+        )
+        return self._overlaps(hvd)
+
+    def _overlaps(self, lines):
+        seen = defaultdict(lambda: 0)
+        for x1, y1, x2, y2 in lines:
+            yn = -1 if y1 > y2 else 1
+            xn = -1 if x1 > x2 else 1
+            if self._diagonal(x1, y1, x2, y2):
+                pl = abs(y1 - y2)
+                for n in range(pl + 1):
+                    seen[(y1 + n * yn, x1 + n * xn)] += 1
+            else:
+                for y in range(min(y1, y2), max(y1, y2) + 1):
+                    for x in range(min(x1, x2), max(x1, x2) + 1):
+                        seen[(y, x)] += 1
+        return sum(map(lambda v: v > 1, seen.values()))
+
+    def _diagonal(self, x1, y1, x2, y2):
+        return abs(x1 - x2) == abs(y1 - y2)
+
+
+if __name__ == "__main__":
+    solution = Solution()
+    solution.show_results()
diff --git a/2021-python/tests/test_day_05.py b/2021-python/tests/test_day_05.py
new file mode 100644
index 0000000..cc91d71
--- /dev/null
+++ b/2021-python/tests/test_day_05.py
@@ -0,0 +1,39 @@
+import unittest
+
+from solutions.day_05 import Solution
+
+
+class Day05TestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+        self.puzzle_input = self.solution.parse_input(
+            """
+        0,9 -> 5,9
+8,0 -> 0,8
+9,4 -> 3,4
+2,2 -> 2,1
+7,0 -> 7,4
+6,4 -> 2,0
+0,9 -> 2,9
+3,4 -> 1,4
+0,0 -> 8,8
+5,5 -> 8,2
+        """
+        )
+
+    def test_parse_puzzle_input(self):
+        data = """
+        11,222 -> 4444,55555
+8,0 -> 0,8
+        """
+        assert self.solution.parse_input(data) == [(11, 222, 4444, 55555), (8, 0, 0, 8)]
+
+    def test_solve_first_part(self):
+        assert self.solution.solve(self.puzzle_input) == 5
+
+    def test_solve_second_part(self):
+        assert self.solution.solve_again(self.puzzle_input) == 12
+
+
+if __name__ == "__main__":
+    unittest.main()