Initial commit

2020/puzzle-06-02.cc

@@ -0,0 +1,61 @@
+#include <algorithm>
+#include <cassert>
+#include <iostream>
+#include <map>
+#include <string>
+
+using OccuranceMap = std::map<char, unsigned>;
+
+struct GroupAnswers {
+  void add_answers(std::string const &a) {
+    // Increase group size
+    ++group_size_;
+
+    // Add answers
+    for (auto c : a) {
+      auto it = map_.find(c);
+      if (it == map_.end()) {
+        map_.insert({c, 1});
+      } else {
+        ++(it->second);
+      }
+    }
+  }
+
+  // Count the number of answered questions answered by everyone.
+  unsigned all_answer_count() const noexcept {
+    unsigned count = 0;
+    for (auto kv : map_) {
+      if (kv.second == group_size_) {
+        ++count;
+      }
+    }
+
+    return count;
+  }
+
+  void clear() {
+    map_.clear();
+    group_size_ = 0;
+  }
+
+  OccuranceMap map_;
+  unsigned group_size_ = 0;
+};
+
+int main(int argc, char **argv) {
+  GroupAnswers answers;
+  unsigned count = 0;
+  for (std::string line; std::getline(std::cin, line);) {
+    if (!line.empty()) {
+      answers.add_answers(line);
+    } else {
+      count += answers.all_answer_count();
+      answers.clear();
+    }
+  }
+  count += answers.all_answer_count();
+
+  std::cout << "Total length = " << count << "\n";
+  return 0;
+}