aoc 2024, day1

1 files changed, 72 insertions, 0 deletions

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);
+}