Add 2018 Day 2 part 2.

2018/puzzle-02-02.cc

@@ -0,0 +1,55 @@
+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <string>
+#include <utility>
+#include <vector>
+
+using Int = std::int64_t;
+
+auto str_dist(std::string const& s1, std::string const& s2) noexcept -> Int
+{
+  Int result{0};
+  for (std::size_t i{0}; i != s1.size(); ++i) {
+    if (s1[i] != s2[i]) {
+      ++result;
+    }
+  }
+  return result;
+}
+
+auto main() -> int
+{
+  std::string line;
+  std::vector<std::string> lines;
+  while (std::getline(std::cin, line)) {
+    lines.push_back(line);
+  }
+
+  Int closest{std::numeric_limits<Int>::max()};
+  std::string s1;
+  std::string s2;
+  for (auto it{lines.begin()}; it != lines.end(); ++it) {
+    for (auto it2{it + 1}; it2 != lines.end(); ++it2) {
+      auto distance{str_dist(*it, *it2)};
+      if (distance < closest) {
+        closest = distance;
+        s1 = *it;
+        s2 = *it2;
+      }
+    }
+  }
+  std::string result;
+  result.reserve(s1.size());
+  for (std::size_t i{0}; i != s1.size(); ++i) {
+    if (s1[i] == s2[i]) {
+      result += s1[i];
+    }
+  }
+
+  std::cout << "Result: " << result << '\n';
+  return EXIT_SUCCESS;
+}