Solutions for 2018 day 14

2018/puzzle-14-01.cc

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+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <array>
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <regex>
+#include <utility>
+
+using Int = std::int64_t;
+using UInt = std::uint64_t;
+using Point = std::pair<Int, Int>;
+
+auto main() -> int
+{
+  std::string line;
+  if (!std::getline(std::cin, line)) {
+    std::cerr << "Unable to read line.\n";
+    return EXIT_FAILURE;
+  }
+  UInt const rounds{std::stoull(line)};
+
+  std::vector<uint8_t> scores;
+  scores.push_back(3);
+  scores.push_back(7);
+  UInt elf1_pos{0};
+  UInt elf2_pos{1};
+
+  while (scores.size() < rounds + 10) {
+    uint8_t const new_score{static_cast<std::uint8_t>(scores[elf1_pos] + scores[elf2_pos])};
+    assert(new_score < 100);
+    if (new_score >= 10) {
+      scores.push_back(new_score / 10);
+    }
+    scores.push_back(new_score % 10);
+    elf1_pos = (elf1_pos + 1 + scores[elf1_pos]) % scores.size();
+    elf2_pos = (elf2_pos + 1 + scores[elf2_pos]) % scores.size();
+  }
+
+  std::cout << "Score: ";
+  for (UInt idx{rounds}; idx < rounds + 10; ++idx) {
+    std::cout << static_cast<UInt>(scores[idx]);
+  }
+  std::cout << "\n";
+}

2018/puzzle-14-02.cc

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+//
+// Created by Matthew Gretton-Dann on 01/12/2022.
+//
+
+#include <array>
+#include <cstdlib>
+#include <iomanip>
+#include <iostream>
+#include <regex>
+#include <utility>
+
+using Int = std::int64_t;
+using UInt = std::uint64_t;
+using Point = std::pair<Int, Int>;
+
+auto main() -> int
+{
+  std::string search;
+  if (!std::getline(std::cin, search)) {
+    std::cerr << "Unable to read line.\n";
+    return EXIT_FAILURE;
+  }
+  std::string scores{"37"};
+  UInt elf1_pos{0};
+  UInt elf2_pos{1};
+
+  UInt rounds{1'000'000};
+  while (true) {
+    while (scores.size() < rounds) {
+      Int const new_score{scores[elf1_pos] - '0' + scores[elf2_pos] - '0'};
+      assert(new_score < 100);
+      if (new_score >= 10) {
+        scores.push_back(static_cast<char>('0' + (new_score / 10)));
+      }
+      scores.push_back(static_cast<char>('0' + (new_score % 10)));
+      elf1_pos = (elf1_pos + 1 + scores[elf1_pos] - '0') % scores.size();
+      elf2_pos = (elf2_pos + 1 + scores[elf2_pos] - '0') % scores.size();
+    }
+    rounds += 1'000'000;
+
+    auto it{scores.find(search)};
+    if (it != std::string::npos) {
+      std::cout << "Search string appears after: " << it << "\n";
+      return EXIT_SUCCESS;
+    }
+  }
+}