From e308ad6691abd5be82e9a2b8819d0ec1549f96de Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sun, 1 Dec 2024 08:20:37 +0100
Subject: aoc 2024, day1

---
 2024/src/day01.cpp | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 2024/src/day01.cpp

(limited to '2024/src')

diff --git a/2024/src/day01.cpp b/2024/src/day01.cpp
new file mode 100644
index 0000000..61b3c29
--- /dev/null
+++ b/2024/src/day01.cpp
@@ -0,0 +1,72 @@
+#include <algorithm>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <tuple>
+#include <vector>
+using namespace std;
+
+vector<tuple<long, long>>
+read_file(string_view filename)
+{
+	fstream                   input{ filename };
+	vector<tuple<long, long>> data;
+
+	long lhs = 0;
+	long rhs = 0;
+
+	while ( input >> lhs >> rhs ) {
+		data.emplace_back(lhs, rhs);
+	}
+
+	return data;
+}
+
+void
+part1(const vector<tuple<long, long>>& data)
+{
+	vector<long> lefts;
+	vector<long> rights;
+
+	for ( const auto& [lhs, rhs]: data ) {
+		lefts.emplace_back(lhs);
+		rights.emplace_back(rhs);
+	}
+
+	sort(lefts.begin(), lefts.end());
+	sort(rights.begin(), rights.end());
+
+	long total_distance = 0;
+	for ( size_t i = 0; i != lefts.size(); ++i ) {
+		long distance = abs(lefts[i] - rights[i]);
+		total_distance += distance;
+	}
+	cout << total_distance << endl;
+}
+
+void
+part2(const vector<tuple<long, long>>& data)
+{
+	vector<long>    lefts;
+	map<long, long> rights;
+
+	for ( const auto& [lhs, rhs]: data ) {
+		lefts.emplace_back(lhs);
+		rights[rhs]++;
+	}
+
+	long score = 0;
+	for ( const auto& lhs: lefts ) {
+		score += lhs * rights[lhs];
+	}
+	cout << score << endl;
+}
+
+int
+main()
+{
+	auto data = read_file("data/day01.txt");
+	part1(data);
+	part2(data);
+}
-- 
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