From 566dbf51f27b6e181826b8de6c1cb98b4a680fe8 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Fri, 15 Nov 2024 16:57:33 +0100
Subject: aoc 2015, days 12, 13 and 14

---
 2015/src/day13.cpp | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 2015/src/day13.cpp

(limited to '2015/src/day13.cpp')

diff --git a/2015/src/day13.cpp b/2015/src/day13.cpp
new file mode 100644
index 0000000..7256b81
--- /dev/null
+++ b/2015/src/day13.cpp
@@ -0,0 +1,108 @@
+#include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <limits>
+#include <map>
+#include <set>
+#include <sstream>
+#include <string>
+#include <tuple>
+#include <vector>
+
+using namespace std;
+
+auto
+split(const string& line, char sep = ' ')
+{
+	vector<string> parts;
+	stringstream   input{ line };
+
+	for ( string part; getline(input, part, sep); ) {
+		parts.emplace_back(part);
+	}
+
+	return parts;
+}
+
+auto
+read_file(string_view filename)
+{
+	fstream                          input{ filename };
+	set<string>                      names;
+	map<tuple<string, string>, long> table;
+
+	for ( string line; getline(input, line); ) {
+		if ( line.ends_with(".") ) {
+			line.pop_back();
+		}
+
+		auto parts = split(line);
+
+		auto start = parts[0];
+		auto units = parts[2] == "gain" ? stol(parts[3]) : -stol(parts[3]);
+		auto end   = parts[10]; // NOLINT
+
+		table[{ start, end }] = units;
+
+		names.insert(start);
+	}
+	return table;
+}
+
+void
+part1(map<tuple<string, string>, long>& table)
+{
+	set<string> unique_names;
+	for ( const auto& item: table ) {
+		unique_names.insert(get<0>(item.first));
+	}
+	vector<string> names{ begin(unique_names), end(unique_names) };
+
+	long happiness_sofar = numeric_limits<long>::min();
+	do {
+		long happiness = 0;
+		for ( size_t idx = 0; idx != names.size(); ++idx ) {
+			auto next_idx = (idx + 1) % names.size();
+
+			happiness += table[{ names[idx], names[next_idx] }];
+			happiness += table[{ names[next_idx], names[idx] }];
+		}
+
+		happiness_sofar = max(happiness_sofar, happiness);
+	} while ( next_permutation(begin(names), end(names)) );
+	cout << happiness_sofar << endl;
+}
+
+void
+part2(map<tuple<string, string>, long>& table)
+{
+	set<string> unique_names;
+	for ( const auto& item: table ) {
+		unique_names.insert(get<0>(item.first));
+	}
+	vector<string> names{ begin(unique_names), end(unique_names) };
+	names.emplace_back("Hartkode");
+
+	long happiness_sofar = numeric_limits<long>::min();
+	do {
+		long happiness = 0;
+		for ( size_t idx = 0; idx != names.size(); ++idx ) {
+			auto next_idx = (idx + 1) % names.size();
+
+			happiness += table[{ names[idx], names[next_idx] }];
+			happiness += table[{ names[next_idx], names[idx] }];
+		}
+
+		happiness_sofar = max(happiness_sofar, happiness);
+	} while ( next_permutation(begin(names), end(names)) );
+	cout << happiness_sofar << endl;
+}
+
+int
+main()
+{
+	auto table = read_file("data/day13.txt");
+	part1(table);
+	part2(table);
+}
-- 
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