From d63c7463ccea8b52a4fdd649355b2ae37c28d906 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anders=20Ytterstr=C3=B6m?= <yttan@fastmail.se>
Date: Thu, 2 Dec 2021 06:42:42 +0100
Subject: [PATCH] Solve 2021:2 "Drive!"

---
 2021-python/solutions/day_02.py  | 38 ++++++++++++++++++++++++++++++++
 2021-python/tests/test_day_02.py | 36 ++++++++++++++++++++++++++++++
 2 files changed, 74 insertions(+)
 create mode 100644 2021-python/solutions/day_02.py
 create mode 100644 2021-python/tests/test_day_02.py

diff --git a/2021-python/solutions/day_02.py b/2021-python/solutions/day_02.py
new file mode 100644
index 0000000..ab3c278
--- /dev/null
+++ b/2021-python/solutions/day_02.py
@@ -0,0 +1,38 @@
+from solutions import BaseSolution
+
+
+class Solution(BaseSolution):
+    input_file = "02.txt"
+
+    def __str__(self):
+        return "Day 2: Drive!"
+
+    def parse_input(self, data):
+        def xy(direction, value):
+            if direction == "forward":
+                return (0, int(value))
+            elif direction == "up":
+                return (-int(value), 0)
+            elif direction == "down":
+                return (int(value), 0)
+
+        return [xy(*l.split()) for l in data.strip().splitlines()]
+
+    def solve(self, puzzle_input):
+        x = sum(map(lambda xy: xy[0], puzzle_input))
+        y = sum(map(lambda xy: xy[1], puzzle_input))
+        return x * y
+
+    def solve_again(self, puzzle_input):
+        pos = (0, 0, 0)
+        for x, y in puzzle_input:
+            if y > 0:
+                pos = (pos[2] * y + pos[0], pos[1] + y, pos[2])
+            else:
+                pos = (pos[0], pos[1], pos[2] + x)
+        return pos[0] * pos[1]
+
+
+if __name__ == "__main__":
+    solution = Solution()
+    solution.show_results()
diff --git a/2021-python/tests/test_day_02.py b/2021-python/tests/test_day_02.py
new file mode 100644
index 0000000..da826c6
--- /dev/null
+++ b/2021-python/tests/test_day_02.py
@@ -0,0 +1,36 @@
+import unittest
+
+from solutions.day_02 import Solution
+
+
+class Day02TestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+        self.puzzle_input = self.solution.parse_input(
+            """
+        forward 5
+down 5
+forward 8
+up 3
+down 8
+forward 2
+        """
+        )
+
+    def test_parse_puzzle_input(self):
+        data = """
+        forward 8
+up 3
+down 8
+        """
+        assert self.solution.parse_input(data) == [(0, 8), (-3, 0), (8, 0)]
+
+    def test_solve_first_part(self):
+        assert self.solution.solve(self.puzzle_input) == 150
+
+    def test_solve_second_part(self):
+        assert self.solution.solve_again(self.puzzle_input) == 900
+
+
+if __name__ == "__main__":
+    unittest.main()