Initial commit

2020/puzzle-21-02.cc

@@ -0,0 +1,143 @@
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <iostream>
+#include <list>
+#include <map>
+#include <regex>
+#include <set>
+#include <string>
+#include <tuple>
+#include <vector>
+
+using Ingredient = std::string;
+using Allergen = std::string;
+using Ingredients = std::set<Ingredient>;
+using Allergens = std::set<Allergen>;
+using IngredientInfo = std::pair<unsigned, Allergens>;
+
+using IngredientMap = std::map<Ingredient, IngredientInfo>;
+using AllergenMap = std::map<Allergen, Ingredients>;
+
+class IngredientParser {
+public:
+  void add_recipe(std::string const &s) {
+    auto it = s.begin();
+    Ingredients i;
+    while (it != s.end()) {
+      auto ite = std::find(it, s.end(), ' ');
+      auto ingredient = std::string(it, ite);
+      while (ite != s.end() && *ite == ' ') {
+        ++ite;
+      }
+      it = ite;
+      if (ingredient == "(contains") {
+        break;
+      } else {
+        i.insert(ingredient);
+        auto [iit, success] =
+            ingredients_.insert({ingredient, {1, Allergens()}});
+        if (!success) {
+          iit->second.first++;
+        }
+      }
+    }
+
+    while (it != s.end()) {
+      auto ite = std::find_if(
+          it, s.end(), [](char c) -> bool { return c == ',' || c == ')'; });
+      auto allergen = std::string(it, ite);
+      ++ite;
+      while (ite != s.end() && *ite == ' ') {
+        ++ite;
+      }
+      it = ite;
+      auto [insert_it, success] = allergens_.insert({allergen, i});
+      if (!success) {
+        Ingredients a;
+        std::set_intersection(i.begin(), i.end(), insert_it->second.begin(),
+                              insert_it->second.end(),
+                              std::inserter(a, a.end()));
+        insert_it->second = a;
+      }
+    }
+  }
+
+  unsigned clean_ingredients() {
+    for (auto const &kv : allergens_) {
+      auto allergen = kv.first;
+      std::cout << "Allergen " << allergen << ":";
+      for (auto const &i : kv.second) {
+        std::cout << " " << i;
+        auto it = ingredients_.find(i);
+        assert(it != ingredients_.end());
+        it->second.second.insert(allergen);
+      }
+      std::cout << "\n";
+    }
+
+    unsigned count = 0;
+    for (auto const &i : ingredients_) {
+      if (i.second.second.size() == 0) {
+        std::cout << i.first << " is not an allergen, appears "
+                  << i.second.first << ".\n";
+        count += i.second.first;
+      }
+    }
+
+    return count;
+  }
+
+  std::string dangerous_ingredients() {
+    bool changed = true;
+    Ingredients i;
+    while (changed) {
+      changed = false;
+      for (auto const &kv : allergens_) {
+        if (kv.second.size() == 1) {
+          auto it = kv.second.begin();
+          Ingredient const &ing = *it;
+          auto [iit, success] = i.insert(ing);
+          if (!success) {
+            continue;
+          }
+          changed = true;
+          std::cout << "Allergen " << kv.first << " is in ingredient " << ing
+                    << "\n";
+          for (auto &kv2 : allergens_) {
+            if (kv2.second.size() != 1) {
+              kv2.second.erase(ing);
+            }
+          }
+        }
+      }
+    }
+
+    std::string result;
+    for (auto const &kv : allergens_) {
+      result += ",";
+      result += *kv.second.begin();
+    }
+
+    return result.substr(1);
+  }
+
+private:
+  IngredientMap ingredients_;
+  AllergenMap allergens_;
+};
+
+int main(void) {
+  std::string line;
+  IngredientParser parser;
+  while (std::getline(std::cin, line)) {
+    parser.add_recipe(line);
+  }
+
+  auto clean = parser.clean_ingredients();
+  std::cout << "Number of clean ingredients: " << clean << "\n";
+
+  auto dangerous = parser.dangerous_ingredients();
+  std::cout << "Dangerous ingredients: " << dangerous << "\n";
+  return 0;
+}