1 files changed, 58 insertions, 0 deletions

diff --git a/2018/src/day01.cpp b/2018/src/day01.cpp
new file mode 100644
index 0000000..d57a187
--- /dev/null
+++ b/2018/src/day01.cpp
@@ -0,0 +1,58 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <numeric>
+#include <unordered_set>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+vector<long>
+read_file(const filesystem::path& filename)
+{
+        ifstream     file{ filename };
+        vector<long> values;
+
+        for ( long value = 0; file >> value; ) {
+                values.emplace_back(value);
+        }
+
+        return values;
+}
+
+void
+part1(const vector<long>& values)
+{
+        auto sum = accumulate(values.begin(), values.end(), 0L);
+        cout << "Part1: " << sum << '\n';
+}
+
+void
+part2(const vector<long>& values)
+{
+        unordered_set<long> seen;
+
+        long sum = 0;
+        for ( size_t idx = 0;; ++idx ) {
+                sum += values.at(idx % values.size());
+
+                if ( seen.contains(sum) ) {
+                        cout << "Part2: " << sum << '\n';
+                        return;
+                }
+
+                seen.emplace(sum);
+        }
+}
+
+} // namespace
+
+int
+main()
+{
+        auto values = read_file("data/day01.txt");
+        part1(values);
+        part2(values);
+}