From 4b6c1b0e539d9fc37b646af5865b75aaa5b49bfc Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Wed, 13 Nov 2024 22:20:30 +0100
Subject: aoc 2015, days 5, 6 and 7

---
 2015/src/day06.cpp | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 2015/src/day06.cpp

(limited to '2015/src/day06.cpp')

diff --git a/2015/src/day06.cpp b/2015/src/day06.cpp
new file mode 100644
index 0000000..b7f15b5
--- /dev/null
+++ b/2015/src/day06.cpp
@@ -0,0 +1,114 @@
+#include <algorithm>
+#include <cstdio>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <numeric>
+#include <string>
+#include <tuple>
+#include <vector>
+
+using namespace std;
+
+enum Operation {
+	On,
+	Off,
+	Toggle
+};
+
+using instruction = tuple<Operation, int, int, int, int>;
+
+auto
+read_file(string_view filename)
+{
+	fstream             input{ filename };
+	vector<instruction> instructions;
+
+	for ( string line; getline(input, line); ) {
+		int x0, y0, x1, y1; // NOLINT
+
+		if ( sscanf(line.c_str(), "turn on %d,%d through %d,%d", &x0, &y0, &x1, &y1) == 4 ) { // NOLINT
+			instructions.emplace_back(Operation::On, x0, y0, x1, y1);
+		}
+		else if ( sscanf(line.c_str(), "toggle %d,%d through %d,%d", &x0, &y0, &x1, &y1) == 4 ) { // NOLINT
+			instructions.emplace_back(Operation::Toggle, x0, y0, x1, y1);
+		}
+		else if ( sscanf(line.c_str(), "turn off %d,%d through %d,%d", &x0, &y0, &x1, &y1) == 4 ) { // NOLINT
+			instructions.emplace_back(Operation::Off, x0, y0, x1, y1);
+		}
+	}
+
+	return instructions;
+}
+
+// clang-format off
+static void turn_on(int& value) { value = 1; }
+static void turn_off(int& value) { value = 0; }
+static void toggle(int& value) { value ^= 1; }
+// clang-format on
+
+void
+part1(const vector<instruction>& instructions)
+{
+	map<Operation, function<void(int&)>> ops = {
+		{ Operation::On, turn_on },
+		{ Operation::Toggle, toggle },
+		{ Operation::Off, turn_off }
+	};
+
+	map<tuple<int, int>, int> lights;
+
+	for ( const auto& [operation, x0, y0, x1, y1]: instructions ) {
+		for ( int x = x0; x <= x1; ++x ) {
+			for ( int y = y0; y <= y1; ++y ) {
+				ops[operation](lights[{ x, y }]);
+			}
+		}
+	}
+
+	auto sum = count_if(begin(lights), end(lights), [](const auto& light) {
+		return light.second == 1;
+	});
+
+	cout << sum << endl;
+}
+
+// clang-format off
+static void increase(int& value) { ++value; }
+static void decrease(int& value) { if (value > 0) { --value; } }
+static void increase_by_2(int& value) { value += 2; }
+// clang-format on
+
+void
+part2(const vector<instruction>& instructions)
+{
+	map<Operation, function<void(int&)>> ops = {
+		{ Operation::On, increase },
+		{ Operation::Toggle, increase_by_2 },
+		{ Operation::Off, decrease }
+	};
+
+	map<tuple<int, int>, int> lights;
+
+	for ( const auto& [operation, x0, y0, x1, y1]: instructions ) {
+		for ( int x = x0; x <= x1; ++x ) {
+			for ( int y = y0; y <= y1; ++y ) {
+				ops[operation](lights[{ x, y }]);
+			}
+		}
+	}
+
+	auto sum = accumulate(begin(lights), end(lights), 0, [](int value, const auto& light) {
+		return value + light.second;
+	});
+
+	cout << sum << endl;
+}
+
+int
+main()
+{
+	auto instructions = read_file("data/day06.txt");
+	part1(instructions);
+	part2(instructions);
+}
-- 
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