1 files changed, 27 insertions, 2 deletions

diff --git a/2025/src/day11.cpp b/2025/src/day11.cpp
index 47440f9..1bf8d44 100644
--- a/2025/src/day11.cpp
+++ b/2025/src/day11.cpp
@@ -64,17 +64,41 @@ part1(const Graph& graph)
                 }
 
                 long count = 0;
-
                 for ( const auto& node: graph.at(src) ) {
                         count += dfs(node);
                 }
-
                 return cache[src] = count;
         };
 
         cout << "Part 1: " << dfs("you") << '\n';
 }
 
+void
+part2(const Graph& graph)
+{
+        map<tuple<string, bool, bool>, long> cache;
+
+        function<long(const string&, bool, bool)> dfs = [&](const string& src, bool dac_visited, bool fft_visited) {
+                if ( src == "out" ) {
+                        return (dac_visited && fft_visited) ? 1L : 0L;
+                }
+
+                const auto args = make_tuple(src, dac_visited, fft_visited);
+
+                if ( cache.contains(args) ) {
+                        return cache.at(args);
+                }
+
+                long count = 0;
+                for ( const auto& node: graph.at(src) ) {
+                        count += dfs(node, dac_visited || node == "dac", fft_visited || node == "fft");
+                }
+                return cache[args] = count;
+        };
+
+        cout << "Part 2: " << dfs("svr", false, false) << '\n';
+}
+
 } // namespace
 
 int
@@ -82,4 +106,5 @@ main()
 {
         auto graph = read_file("data/day11.txt");
         part1(graph);
+        part2(graph);
 }