1 files changed, 75 insertions, 0 deletions

diff --git a/2017/src/day09.cpp b/2017/src/day09.cpp
new file mode 100644
index 0000000..60b0d3b
--- /dev/null
+++ b/2017/src/day09.cpp
@@ -0,0 +1,75 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <string>
+
+using namespace std;
+
+namespace {
+
+string
+remove_garbage(string_view line, int& removed)
+{
+        string result;
+
+        removed = 0;
+        for ( size_t pos = 0; pos < line.size(); ) {
+                if ( line.at(pos) == '<' ) {
+                        ++pos;
+                        while ( pos < line.size() && line.at(pos) != '>' ) {
+                                if ( line.at(pos) == '!' ) {
+                                        pos += 2;
+                                }
+                                else {
+                                        ++pos;
+                                        ++removed;
+                                }
+                        }
+                        ++pos;
+                }
+                else {
+                        result += line.at(pos);
+                        ++pos;
+                }
+        }
+
+        return result;
+}
+
+string
+read_file(const filesystem::path& filename)
+{
+        ifstream file{ filename };
+        return { istreambuf_iterator<char>{ file }, {} };
+}
+
+void
+solve(string_view data)
+{
+        int score   = 0;
+        int depth   = 0;
+        int removed = 0;
+
+        for ( const auto chr: remove_garbage(data, removed) ) {
+                if ( chr == '{' ) {
+                        ++depth;
+                }
+                else if ( chr == '}' ) {
+                        score += depth;
+                        --depth;
+                }
+        }
+
+        cout << "Part1: " << score << '\n';
+        cout << "Part2: " << removed << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+        auto data = read_file("data/day09.txt");
+        solve(data);
+}