Initial commit

2015/puzzle-15-01.cc

@@ -0,0 +1,123 @@
+#include <cassert>
+#include <cctype>
+#include <climits>
+#include <functional>
+#include <iostream>
+#include <map>
+#include <regex>
+#include <set>
+#include <string>
+#include <variant>
+
+using Score = long;
+using PropertyMap = std::map<std::string, Score>;
+
+struct Ingredient {
+  explicit Ingredient(std::string const &s) {
+    auto colon = s.find(':');
+    name_ = s.substr(0, colon);
+    auto suffix = s.substr(colon + 1);
+    std::cout << name_ << "\n";
+    while (!suffix.empty()) {
+      static const std::regex re(",? (\\w+) (-?\\d+)");
+      std::smatch m;
+      if (std::regex_search(suffix, m, re)) {
+        auto [it, success] =
+            properties_.insert({m.str(1), std::stol(m.str(2))});
+        assert(success);
+        std::cout << "  " << it->first << ": " << it->second << "\n";
+        suffix = m.suffix();
+      } else {
+        assert(false);
+      }
+    }
+  }
+
+  bool operator<(Ingredient const &rhs) const noexcept {
+    return name_ < rhs.name_;
+  }
+
+  std::string const &name() const noexcept { return name_; }
+
+  void update_score(Score amount, PropertyMap &totals) const {
+    for (auto const &kv : properties_) {
+      if (kv.first == "calories") {
+        continue;
+      }
+      auto [it, success] = totals.insert({kv.first, amount * kv.second});
+      if (!success) {
+        it->second += amount * kv.second;
+      }
+    }
+  }
+
+private:
+  std::string name_;
+  PropertyMap properties_;
+};
+
+struct Ingredients {
+  void add_ingredient(std::string const &s) {
+    ingredients_.push_back(Ingredient(s));
+  }
+
+  Score best_combination(Score amount) const {
+    PropertyMap totals;
+    return best_combination(amount, ingredients_.begin(), 0UL, totals);
+  }
+
+private:
+  Score best_combination(Score amount,
+                         std::vector<Ingredient>::const_iterator it,
+                         Score best_score, PropertyMap &totals) const {
+    it->update_score(amount, totals);
+    auto it2 = it;
+    ++it2;
+    if (it2 == ingredients_.end()) {
+      auto score = calculate_score(totals);
+      best_score = std::max(best_score, score);
+      it->update_score(-amount, totals);
+      return best_score;
+    }
+
+    for (auto allocation = amount - 1; allocation > 0; --allocation) {
+      it->update_score(-1, totals);
+      best_score =
+          std::max(best_score, best_combination(amount - allocation, it2,
+                                                best_score, totals));
+    }
+    it->update_score(-1, totals);
+
+    return best_score;
+  }
+
+  Score calculate_score(PropertyMap const &totals) const {
+    Score r = 1;
+    for (auto const &kv : totals) {
+      if (kv.first == "calories") {
+        continue;
+      }
+      if (kv.second < 0) {
+        return 0;
+      }
+      r *= kv.second;
+    }
+
+    return r;
+  }
+
+  std::vector<Ingredient> ingredients_;
+};
+
+int main(int argc, char **argv) {
+  Ingredients ingredients;
+
+  std::string line;
+  while (std::getline(std::cin, line)) {
+    ingredients.add_ingredient(line);
+  }
+
+  auto r = ingredients.best_combination(100);
+  std::cout << "Solution: " << r << "\n";
+  return 0;
+}