1 files changed, 17 insertions, 1 deletions
diff --git a/src/2017/day21/aoc.cpp b/src/2017/day21/aoc.cpp
index 716d4e6..b1f315a 100644
--- a/src/2017/day21/aoc.cpp
+++ b/src/2017/day21/aoc.cpp
@@ -3,6 +3,20 @@
 
 namespace aoc2017 {
 
+typedef void (*sfunc)(std::vector<square3>* vs3, std::vector<square2>* vs2,
+                      const std::map<std::string, std::string>& rs);
+void s3tos2(std::vector<square3>* vs3, std::vector<square2>* vs2, const std::map<std::string, std::string>& rs) {}
+void s2tos3(std::vector<square3>* vs3, std::vector<square2>* vs2, const std::map<std::string, std::string>& rs) {}
+
+static void part1(int t, int times, std::vector<square3>* vs3, std::vector<square2>* vs2,
+                  const std::map<std::string, std::string>& rs) {
+  sfunc fs[2] = {s3tos2, s2tos3};
+  if (t <= times) {
+    sfunc f = fs[t % 2];
+    f(vs3, vs2, rs);
+  }
+}
+
 std::pair<int64_t, int64_t> day21(line_view file) {
   std::map<std::string, std::string> rules;
 
@@ -28,7 +42,9 @@ std::pair<int64_t, int64_t> day21(line_view file) {
   // .#.
   // ..#
   // ###
-  square3 s3{".#./..#/###"};
+  std::vector<square3> vs3{{".#./..#/###"}};
+  std::vector<square2> vs2;
+  part1(1, 5, &vs3, &vs2, rules);
 
   // for (auto& kv : rules) {
   //   printf("%s => %s\n", kv.first.c_str(), kv.second.c_str());