diff --git a/2017/puzzle-12-01.cc b/2017/puzzle-12-01.cc
new file mode 100644
index 0000000..543533a
--- /dev/null
+++ b/2017/puzzle-12-01.cc
@@ -0,0 +1,64 @@
+#include <cassert>
+#include <iostream>
+#include <map>
+#include <string>
+
+struct InTree
+{
+  constexpr auto visited() const noexcept -> bool { return visited_; }
+  constexpr void visit() { visited_ = true; }
+
+private:
+  bool visited_{false};
+};
+
+using UInt = unsigned long;
+using VisitMap = std::map<UInt, InTree>;
+using Connections = std::multimap<UInt, UInt>;
+
+auto find_next_node(VisitMap& map)
+{
+  return std::find_if(map.begin(), map.end(), [](auto const& it) { return !it.second.visited(); });
+}
+
+auto main() -> int
+{
+  std::string line;
+  Connections connections;
+
+  while (std::getline(std::cin, line) && !line.empty()) {
+    std::size_t end{0};
+    auto from{std::stoul(line, &end)};
+    assert(line.substr(end, 5) == " <-> ");
+    auto idx{end + 5};
+    while (idx < line.size()) {
+      if (line[idx] == ',' || line[idx] == ' ') {
+        ++idx;
+        continue;
+      }
+
+      auto to{std::stoul(line.substr(idx), &end)};
+      connections.insert({from, to});
+      connections.insert({to, from});
+      idx += end;
+    }
+  }
+
+  VisitMap connected0;
+  connected0.insert({0, InTree{}});
+  while (true) {
+    auto it{find_next_node(connected0)};
+    if (it == connected0.end()) {
+      break;
+    }
+    it->second.visit();
+
+    auto [it_begin, it_end] = connections.equal_range(it->first);
+    for (auto it2{it_begin}; it2 != it_end; ++it2) {
+      connected0.insert({it2->second, InTree{}});
+    }
+  }
+
+  std::cout << "Size of connected tree: " << connected0.size() << '\n';
+  return 0;
+}
diff --git a/2017/puzzle-12-02.cc b/2017/puzzle-12-02.cc
new file mode 100644
index 0000000..abff189
--- /dev/null
+++ b/2017/puzzle-12-02.cc
@@ -0,0 +1,60 @@
+#include <cassert>
+#include <iostream>
+#include <map>
+#include <string>
+
+using UInt = unsigned long;
+using VisitMap = std::map<UInt, bool>;
+using Connections = std::multimap<UInt, UInt>;
+
+auto find_next_node(VisitMap& map)
+{
+  return std::find_if(map.begin(), map.end(), [](auto const& it) { return !it.second; });
+}
+
+auto main() -> int
+{
+  std::string line;
+  Connections connections;
+
+  while (std::getline(std::cin, line) && !line.empty()) {
+    std::size_t end{0};
+    auto from{std::stoul(line, &end)};
+    assert(line.substr(end, 5) == " <-> ");
+    auto idx{end + 5};
+    while (idx < line.size()) {
+      if (line[idx] == ',' || line[idx] == ' ') {
+        ++idx;
+        continue;
+      }
+
+      auto to{std::stoul(line.substr(idx), &end)};
+      connections.insert({from, to});
+      connections.insert({to, from});
+      idx += end;
+    }
+  }
+
+  UInt group_count{0};
+  while (!connections.empty()) {
+    VisitMap connected;
+    connected.insert({connections.begin()->first, false});
+    while (true) {
+      auto it{find_next_node(connected)};
+      if (it == connected.end()) {
+        break;
+      }
+      it->second = true;
+
+      auto [it_begin, it_end] = connections.equal_range(it->first);
+      for (auto it2{it_begin}; it2 != it_end; ++it2) {
+        connected.insert({it2->second, false});
+      }
+      connections.erase(it_begin, it_end);
+    }
+    ++group_count;
+  }
+
+  std::cout << "Number of groups: " << group_count << '\n';
+  return 0;
+}