Add 2018 Day 2 Part 1

2018/puzzle-02-01.cc

@@ -0,0 +1,45 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <map>
+#include <string>
+#include <utility>
+
+using Int = std::int64_t;
+
+auto has_pairs_triplets(std::string const& s) -> std::pair<bool, bool>
+{
+  std::map<char, Int> counts;
+  for (auto c : s) {
+    auto it = counts.find(c);
+    if (it == counts.end()) {
+      counts.insert({c, 1});
+    }
+    else {
+      ++(it->second);
+    }
+  }
+
+  bool has_pairs{std::any_of(counts.begin(), counts.end(), [](auto x) { return x.second == 2; })};
+  bool has_triplets{std::any_of(counts.begin(), counts.end(), [](auto x) { return x.second == 3; })};
+  return std::make_pair(has_pairs, has_triplets);
+}
+
+auto main() -> int
+{
+  Int num_pairs{0};
+  Int num_triplets{0};
+  std::string line;
+  while (std::getline(std::cin, line)) {
+    auto [has_pair, has_triplet] = has_pairs_triplets(line);
+    if (has_pair) { ++ num_pairs; }
+    if (has_triplet) { ++ num_triplets;}
+  }
+  std::cout << "Num pairs: " << num_pairs << '\n';
+  std::cout << "Num triplets: " << num_triplets << '\n';
+  std::cout << "Result: " << num_pairs * num_triplets << '\n';
+  return EXIT_SUCCESS;
+}