aoc 2017, days 1-20

1 files changed, 82 insertions, 0 deletions

diff --git a/2017/src/day06.cpp b/2017/src/day06.cpp
new file mode 100644
index 0000000..596ca2c
--- /dev/null
+++ b/2017/src/day06.cpp
@@ -0,0 +1,82 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <set>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+vector<int>
+read_lines(const filesystem::path& filename)
+{
+        ifstream    file{ filename };
+        vector<int> lines;
+
+        for ( int value{}; file >> value; ) {
+                lines.emplace_back(value);
+        }
+
+        return lines;
+}
+
+void
+distribute(vector<int>& values)
+{
+        auto iter      = ranges::max_element(values);
+        auto max_value = *iter;
+
+        *iter = 0;
+
+        while ( max_value-- > 0 ) {
+                ++iter;
+                if ( iter == values.end() ) {
+                        iter = values.begin();
+                }
+                *iter += 1;
+        }
+}
+
+void
+part1(vector<int> values)
+{
+        set<vector<int>> seen;
+        for ( int step = 0;; ++step ) {
+                if ( seen.contains(values) ) {
+                        cout << "Part1: " << step << '\n';
+                        return;
+                }
+
+                seen.insert(values);
+
+                distribute(values);
+        }
+}
+
+void
+part2(vector<int> values)
+{
+        map<vector<int>, int> seen;
+        for ( int step = 0;; ++step ) {
+                if ( seen.contains(values) ) {
+                        cout << "Part2: " << step - seen.at(values) << '\n';
+                        return;
+                }
+
+                seen.emplace(values, step);
+
+                distribute(values);
+        }
+}
+
+} // namespace
+
+int
+main()
+{
+        auto values = read_lines("data/day06.txt");
+        part1(values);
+        part2(values);
+}