Add 2017 day 8 puzzles

2017/puzzle-08-01.cc

@@ -0,0 +1,112 @@
+#include <iostream>
+#include <regex>
+#include <string>
+
+using Int = long;
+
+enum class Action { inc, dec };
+
+auto to_action(std::string const& s) -> Action
+{
+  if (s == "inc") {
+    return Action::inc;
+  }
+  if (s == "dec") {
+    return Action::dec;
+  }
+  abort();
+}
+
+enum class Comparison {
+  less_than,
+  less_than_equal,
+  equal,
+  not_equal,
+  greater_than,
+  greater_than_equal
+};
+
+auto to_comparison(std::string const& s) -> Comparison
+{
+  if (s == "<") {
+    return Comparison::less_than;
+  }
+  if (s == "<=") {
+    return Comparison::less_than_equal;
+  }
+  if (s == "==") {
+    return Comparison::equal;
+  }
+  if (s == "!=") {
+    return Comparison::not_equal;
+  }
+  if (s == ">") {
+    return Comparison::greater_than;
+  }
+  if (s == ">=") {
+    return Comparison::greater_than_equal;
+  }
+  abort();
+}
+
+auto compare(Int l, Comparison c, Int r) -> bool
+{
+  switch (c) {
+  case Comparison::less_than:
+    return l < r;
+  case Comparison::less_than_equal:
+    return l <= r;
+  case Comparison::equal:
+    return l == r;
+  case Comparison::not_equal:
+    return l != r;
+  case Comparison::greater_than_equal:
+    return l >= r;
+  case Comparison::greater_than:
+    return l > r;
+  }
+  abort();
+}
+
+auto main() -> int
+{
+  static std::regex cmd_re{"([a-z]+) (...) (-?\\d+) if ([a-z]+) (.+) (-?\\d+)"};
+
+  std::map<std::string, Int> registers;
+  std::string line;
+
+  while (std::getline(std::cin, line) && !line.empty()) {
+    std::smatch m;
+    if (!std::regex_search(line, m, cmd_re)) {
+      std::cerr << "Unable to match: " << line << '\n';
+      return 1;
+    }
+
+    std::string dest_reg{m.str(1)};
+    Action act{to_action(m.str(2))};
+    Int delta{std::stol(m.str(3))};
+    std::string cmp_reg{m.str(4)};
+    Comparison cmp{to_comparison(m.str(5))};
+    Int cmp_value{std::stol(m.str(6))};
+
+    auto cmp_it{registers.find(cmp_reg)};
+    bool cmp_pass{compare(cmp_it == registers.end() ? 0 : cmp_it->second, cmp, cmp_value)};
+
+    if (cmp_pass) {
+      if (act == Action::dec) {
+        delta = -delta;
+      }
+      auto [it, success] = registers.insert({dest_reg, delta});
+      if (!success) {
+        it->second += delta;
+      }
+    }
+  }
+
+  auto largest_it{
+    std::max_element(registers.begin(), registers.end(),
+                     [](auto const& l, auto const& r) { return l.second < r.second; })};
+
+  std::cout << "Largest register: " << largest_it->first << "\nHas value: " << largest_it->second
+            << '\n';
+}

2017/puzzle-08-02.cc

@@ -0,0 +1,118 @@
+#include <iostream>
+#include <limits>
+#include <regex>
+#include <string>
+
+using Int = long;
+
+enum class Action { inc, dec };
+
+auto to_action(std::string const& s) -> Action
+{
+  if (s == "inc") {
+    return Action::inc;
+  }
+  if (s == "dec") {
+    return Action::dec;
+  }
+  abort();
+}
+
+enum class Comparison {
+  less_than,
+  less_than_equal,
+  equal,
+  not_equal,
+  greater_than,
+  greater_than_equal
+};
+
+auto to_comparison(std::string const& s) -> Comparison
+{
+  if (s == "<") {
+    return Comparison::less_than;
+  }
+  if (s == "<=") {
+    return Comparison::less_than_equal;
+  }
+  if (s == "==") {
+    return Comparison::equal;
+  }
+  if (s == "!=") {
+    return Comparison::not_equal;
+  }
+  if (s == ">") {
+    return Comparison::greater_than;
+  }
+  if (s == ">=") {
+    return Comparison::greater_than_equal;
+  }
+  abort();
+}
+
+auto compare(Int l, Comparison c, Int r) -> bool
+{
+  switch (c) {
+  case Comparison::less_than:
+    return l < r;
+  case Comparison::less_than_equal:
+    return l <= r;
+  case Comparison::equal:
+    return l == r;
+  case Comparison::not_equal:
+    return l != r;
+  case Comparison::greater_than_equal:
+    return l >= r;
+  case Comparison::greater_than:
+    return l > r;
+  }
+  abort();
+}
+
+auto main() -> int
+{
+  static std::regex cmd_re{"([a-z]+) (...) (-?\\d+) if ([a-z]+) (.+) (-?\\d+)"};
+
+  std::map<std::string, Int> registers;
+  std::string line;
+  Int largest_value{std::numeric_limits<Int>::min()};
+
+  while (std::getline(std::cin, line) && !line.empty()) {
+    std::smatch m;
+    if (!std::regex_search(line, m, cmd_re)) {
+      std::cerr << "Unable to match: " << line << '\n';
+      return 1;
+    }
+
+    std::string dest_reg{m.str(1)};
+    Action act{to_action(m.str(2))};
+    Int delta{std::stol(m.str(3))};
+    std::string cmp_reg{m.str(4)};
+    Comparison cmp{to_comparison(m.str(5))};
+    Int cmp_value{std::stol(m.str(6))};
+
+    auto cmp_it{registers.find(cmp_reg)};
+    bool cmp_pass{compare(cmp_it == registers.end() ? 0 : cmp_it->second, cmp, cmp_value)};
+
+    if (cmp_pass) {
+      if (act == Action::dec) {
+        delta = -delta;
+      }
+      auto [it, success] = registers.insert({dest_reg, delta});
+      if (!success) {
+        it->second += delta;
+      }
+      if (it->second > largest_value) {
+        largest_value = it->second;
+      }
+    }
+  }
+
+  auto largest_it{
+    std::max_element(registers.begin(), registers.end(),
+                     [](auto const& l, auto const& r) { return l.second < r.second; })};
+
+  std::cout << "Largest register: " << largest_it->first << "\nHas value: " << largest_it->second
+            << '\n';
+  std::cout << "Largest value seen: " << largest_value << '\n';
+}