diff --git a/2018/puzzle-04-01.cc b/2018/puzzle-04-01.cc
new file mode 100644
index 0000000..2668b03
--- /dev/null
+++ b/2018/puzzle-04-01.cc
@@ -0,0 +1,148 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <map>
+#include <numeric>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+using UInt = std::uint64_t;
+
+using namespace std::string_literals;
+
+struct Event
+{
+  explicit Event(std::string const& s)
+  {
+    UInt pos{1};
+    std::size_t l{0};
+    std::stoull(s.substr(pos));
+    timestamp_ = std::stoull(s.substr(pos), &l);  // year
+    pos += l + 1;
+    timestamp_ *= 12;
+    timestamp_ += std::stoull(s.substr(pos), &l) - 1;  // month
+    pos += l + 1;
+    timestamp_ *= 31;                                  // Just need order not actual values.
+    timestamp_ += std::stoull(s.substr(pos), &l) - 1;  // day
+    pos += l + 1;
+    timestamp_ *= 24;
+    timestamp_ += std::stoull(s.substr(pos), &l);  // hour
+    pos += l + 1;
+    timestamp_ *= 60;
+    timestamp_ += std::stoull(s.substr(pos), &l);  // minute
+    pos += l + 2;
+    if (s.substr(pos) == "falls asleep"s) {
+      wake_up_ = false;
+      guard_ = 0;
+    }
+    else if (s.substr(pos) == "wakes up"s) {
+      wake_up_ = true;
+      guard_ = 0;
+    }
+    else {
+      wake_up_ = true;
+      guard_ = std::stoull(s.substr(pos + 7));
+      assert(guard_ != 0);
+    }
+  }
+
+  [[nodiscard]] auto wakes_up() const noexcept -> bool { return wake_up_; }
+  [[nodiscard]] auto guard_id() const noexcept -> UInt { return guard_; }
+  [[nodiscard]] auto timestamp() const noexcept -> UInt { return timestamp_; }
+
+  [[nodiscard]] auto operator<(Event const& r) const noexcept -> bool
+  {
+    if (timestamp_ < r.timestamp_) {
+      return true;
+    }
+    if (timestamp_ > r.timestamp_) {
+      return false;
+    }
+    if (r.wake_up_) {
+      return false;
+    }
+    return wake_up_;
+  }
+
+private:
+  UInt timestamp_{0};
+  UInt guard_{0};
+  bool wake_up_{false};
+};
+
+auto print_timestamp(UInt timestamp)
+{
+  std::cout << "[" << timestamp << ": " << timestamp / static_cast<UInt>(24 * 60 * 31 * 12) << "-"
+            << std::setw(2) << std::setfill('0')
+            << 1 + timestamp / static_cast<UInt>(24 * 60 * 31) % 12 << "-" << std::setw(2)
+            << std::setfill('0') << 1 + (timestamp / static_cast<UInt>(24 * 60)) % 31 << " "
+            << std::setw(2) << std::setfill('0') << (timestamp / 60) % 24 << ":" << std::setw(2)
+            << std::setfill('0') << timestamp % 60 << "]";
+}
+
+auto how_sleepy(std::vector<UInt> const& guard) -> UInt
+{
+  return std::accumulate(guard.begin(), guard.end(), UInt{0}, [](UInt a, UInt b) { return a + b; });
+}
+
+auto main() -> int
+{
+  std::string line;
+  std::vector<Event> events;
+
+  while (std::getline(std::cin, line)) {
+    events.emplace_back(line);
+  }
+  std::sort(events.begin(), events.end());
+  std::map<UInt, std::vector<UInt>> guard_sleep_map;
+  auto current_it{guard_sleep_map.begin()};
+  UInt asleep_from{0};
+
+  for (auto const& e : events) {
+    if (e.wakes_up()) {
+      if (e.guard_id() != 0) {
+        auto result = guard_sleep_map.insert({e.guard_id(), std::vector<UInt>(60, 0)});
+        current_it = result.first;
+        assert(asleep_from == 0);
+        print_timestamp(e.timestamp());
+        std::cout << ": Guard " << current_it->first << " starts duty.\n";
+      }
+      else {
+        assert(asleep_from != 0);
+        for (UInt i = asleep_from; i != e.timestamp(); ++i) {
+          ++(current_it->second[i % 60]);
+        }
+        print_timestamp(e.timestamp());
+        std::cout << ": Guard " << current_it->first << " wakes up after "
+                  << e.timestamp() - asleep_from << " minutes sleep.  Has slept a total of "
+                  << how_sleepy(current_it->second) << " minutes.\n";
+        asleep_from = 0;
+      }
+    }
+    else {
+      assert(asleep_from == 0);
+      asleep_from = e.timestamp();
+      print_timestamp(e.timestamp());
+      std::cout << ": Guard " << current_it->first << " goes to sleep.\n";
+    }
+  }
+
+  auto sleepiest_guard{std::max_element(guard_sleep_map.begin(), guard_sleep_map.end(),
+                                        [](auto const& lhs, auto const& rhs) {
+                                          return how_sleepy(lhs.second) < how_sleepy(rhs.second);
+                                        })};
+  auto sleepiest_guard_id{sleepiest_guard->first};
+  auto sleepiest_minute{
+    std::max_element(sleepiest_guard->second.begin(), sleepiest_guard->second.end()) -
+    sleepiest_guard->second.begin()};
+  std::cout << "Busiest guard: " << sleepiest_guard_id << " was asleep most in minute "
+            << sleepiest_minute << "\n";
+  std::cout << "Result: " << sleepiest_guard_id * sleepiest_minute << "\n";
+  return EXIT_SUCCESS;
+}
diff --git a/2018/puzzle-04-02.cc b/2018/puzzle-04-02.cc
new file mode 100644
index 0000000..419e159
--- /dev/null
+++ b/2018/puzzle-04-02.cc
@@ -0,0 +1,153 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <map>
+#include <numeric>
+#include <set>
+#include <string>
+#include <utility>
+#include <vector>
+
+using UInt = std::uint64_t;
+
+using namespace std::string_literals;
+
+struct Event
+{
+  explicit Event(std::string const& s)
+  {
+    UInt pos{1};
+    std::size_t l{0};
+    std::stoull(s.substr(pos));
+    timestamp_ = std::stoull(s.substr(pos), &l);  // year
+    pos += l + 1;
+    timestamp_ *= 12;
+    timestamp_ += std::stoull(s.substr(pos), &l) - 1;  // month
+    pos += l + 1;
+    timestamp_ *= 31;                                  // Just need order not actual values.
+    timestamp_ += std::stoull(s.substr(pos), &l) - 1;  // day
+    pos += l + 1;
+    timestamp_ *= 24;
+    timestamp_ += std::stoull(s.substr(pos), &l);  // hour
+    pos += l + 1;
+    timestamp_ *= 60;
+    timestamp_ += std::stoull(s.substr(pos), &l);  // minute
+    pos += l + 2;
+    if (s.substr(pos) == "falls asleep"s) {
+      wake_up_ = false;
+      guard_ = 0;
+    }
+    else if (s.substr(pos) == "wakes up"s) {
+      wake_up_ = true;
+      guard_ = 0;
+    }
+    else {
+      wake_up_ = true;
+      guard_ = std::stoull(s.substr(pos + 7));
+      assert(guard_ != 0);
+    }
+  }
+
+  [[nodiscard]] auto wakes_up() const noexcept -> bool { return wake_up_; }
+  [[nodiscard]] auto guard_id() const noexcept -> UInt { return guard_; }
+  [[nodiscard]] auto timestamp() const noexcept -> UInt { return timestamp_; }
+
+  [[nodiscard]] auto operator<(Event const& r) const noexcept -> bool
+  {
+    if (timestamp_ < r.timestamp_) {
+      return true;
+    }
+    if (timestamp_ > r.timestamp_) {
+      return false;
+    }
+    if (r.wake_up_) {
+      return false;
+    }
+    return wake_up_;
+  }
+
+private:
+  UInt timestamp_{0};
+  UInt guard_{0};
+  bool wake_up_{false};
+};
+
+auto print_timestamp(UInt timestamp)
+{
+  std::cout << "[" << timestamp << ": " << timestamp / static_cast<UInt>(24 * 60 * 31 * 12) << "-"
+            << std::setw(2) << std::setfill('0')
+            << 1 + timestamp / static_cast<UInt>(24 * 60 * 31) % 12 << "-" << std::setw(2)
+            << std::setfill('0') << 1 + (timestamp / static_cast<UInt>(24 * 60)) % 31 << " "
+            << std::setw(2) << std::setfill('0') << (timestamp / 60) % 24 << ":" << std::setw(2)
+            << std::setfill('0') << timestamp % 60 << "]";
+}
+
+auto how_sleepy(std::vector<UInt> const& guard) -> UInt
+{
+  return std::accumulate(guard.begin(), guard.end(), UInt{0}, [](UInt a, UInt b) { return a + b; });
+}
+
+auto main() -> int
+{
+  std::string line;
+  std::vector<Event> events;
+
+  while (std::getline(std::cin, line)) {
+    events.emplace_back(line);
+  }
+  std::sort(events.begin(), events.end());
+  std::map<UInt, std::vector<UInt>> guard_sleep_map;
+  auto current_it{guard_sleep_map.begin()};
+  UInt asleep_from{0};
+
+  for (auto const& e : events) {
+    if (e.wakes_up()) {
+      if (e.guard_id() != 0) {
+        auto result = guard_sleep_map.insert({e.guard_id(), std::vector<UInt>(60, 0)});
+        current_it = result.first;
+        assert(asleep_from == 0);
+        print_timestamp(e.timestamp());
+        std::cout << ": Guard " << current_it->first << " starts duty.\n";
+      }
+      else {
+        assert(asleep_from != 0);
+        for (UInt i = asleep_from; i != e.timestamp(); ++i) {
+          ++(current_it->second[i % 60]);
+        }
+        print_timestamp(e.timestamp());
+        std::cout << ": Guard " << current_it->first << " wakes up after "
+                  << e.timestamp() - asleep_from << " minutes sleep.  Has slept a total of "
+                  << how_sleepy(current_it->second) << " minutes.\n";
+        asleep_from = 0;
+      }
+    }
+    else {
+      assert(asleep_from == 0);
+      asleep_from = e.timestamp();
+      print_timestamp(e.timestamp());
+      std::cout << ": Guard " << current_it->first << " goes to sleep.\n";
+    }
+  }
+
+  UInt max_minute{0};
+  UInt max_score{0};
+  for (auto const& guard_sleep : guard_sleep_map) {
+    auto sleepiest_minute{std::max_element(guard_sleep.second.begin(), guard_sleep.second.end())};
+    UInt const score{guard_sleep.first * (sleepiest_minute - guard_sleep.second.begin())};
+    if (*sleepiest_minute > max_minute) {
+      max_score = score;
+      max_minute = *sleepiest_minute;
+    }
+
+    std::cout << "Guard " << guard_sleep.first << " slept most for " << *sleepiest_minute
+              << " minutes at " << sleepiest_minute - guard_sleep.second.begin()
+              << " score: " << score << "\n";
+  }
+
+  std::cout << "Result: " << max_score << "\n";
+  return EXIT_SUCCESS;
+}