From a9d41ba4fdfd3f0be4f191f18866647892aad077 Mon Sep 17 00:00:00 2001
From: Gnarwhal <git.aspect893@passmail.net>
Date: Fri, 11 Dec 2020 21:33:26 -0800
Subject: [PATCH] Completed day 12

---
 2020/days/day12.cpp | 104 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 2020/days/day12.cpp

diff --git a/2020/days/day12.cpp b/2020/days/day12.cpp
new file mode 100644
index 0000000..cc0ee01
--- /dev/null
+++ b/2020/days/day12.cpp
@@ -0,0 +1,104 @@
+/*******************************************************************************
+ *
+ * Copyright (c) 2020 Gnarwhal
+ *
+ * -----------------------------------------------------------------------------
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files(the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ *******************************************************************************/
+
+#include <vector>
+#include <string>
+#include <iostream>
+#include <fstream>
+
+#include "../misc/types.hpp"
+#include "../misc/print.hpp"
+
+struct Instruction{ char op; i32 num; };
+
+auto day12() -> void {
+	auto instructions = std::vector<Instruction>();
+	{
+		auto line = std::string();
+		auto file = std::ifstream("inputs/day12.input");
+		while (getline(file, line)) {
+			instructions.push_back({ line[0], std::stoi(line.substr(1, line.size() - 1)) });
+			if (line[0] == 'L' || line[0] == 'R') {
+				instructions[instructions.size() - 1].num /= 90;
+			}
+		}
+	}
+
+	{
+		auto ship_x = i32(0);
+		auto ship_y = i32(0);
+		auto direction = i32(2);
+		for (const auto & instruction : instructions) {
+			switch (instruction.op) {
+				case 'N': ship_y += instruction.num; break;
+				case 'E': ship_x += instruction.num; break;
+				case 'S': ship_y -= instruction.num; break;
+				case 'W': ship_x -= instruction.num; break;
+				case 'R': direction = (direction - instruction.num + 4) % 4; break;
+				case 'L': direction = (direction + instruction.num    ) % 4; break;
+				case 'F':
+					ship_x += ((direction - 1) % 2) * instruction.num;
+					ship_y += ((direction - 2) % 2) * instruction.num;
+					break;
+			}
+		}
+		print((std::abs(ship_x) + std::abs(ship_y)));
+	}
+
+	{
+		auto ship_x = i32(0);
+		auto ship_y = i32(0);
+		auto waypoint_x = i32(10);
+		auto waypoint_y = i32( 1);
+		for (const auto & instruction : instructions) {
+			switch (instruction.op) {
+				case 'N': waypoint_y += instruction.num; break;
+				case 'E': waypoint_x += instruction.num; break;
+				case 'S': waypoint_y -= instruction.num; break;
+				case 'W': waypoint_x -= instruction.num; break;
+				case 'R':
+					for (auto i = i32(0); i < instruction.num; ++i) {
+						auto copy = waypoint_x;
+						waypoint_x =  waypoint_y;
+						waypoint_y = -copy;
+					}
+					break;
+				case 'L':
+					for (auto i = i32(0); i < instruction.num; ++i) {
+						auto copy = waypoint_x;
+						waypoint_x = -waypoint_y;
+						waypoint_y =  copy;
+					}
+					break;
+				case 'F':
+					ship_x += waypoint_x * instruction.num;
+					ship_y += waypoint_y * instruction.num;
+					break;
+			}
+		}
+		print((std::abs(ship_x) + std::abs(ship_y)));
+	}
+}