2023 Day 12 Part 1

2023/puzzle-12-01.cc

@@ -0,0 +1,93 @@
+#include <cstdint>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+using UInt = std::uint64_t;
+using StringVec = std::vector<std::string>;
+using UIntVec = std::vector<UInt>;
+using Pos = std::pair<UInt, UInt>;
+using PosVec = std::vector<Pos>;
+
+auto split(std::string_view line) -> std::pair<std::string_view, UIntVec>
+{
+  auto pos = line.find(' ');
+  auto pattern = line.substr(0, pos);
+  UIntVec nums;
+
+  line = line.substr(pos);
+  while (!line.empty()) {
+    line = line.substr(1);
+    char* n{nullptr};
+    nums.emplace_back(std::strtoll(line.data(), &n, 10));
+    line = line.substr(n - line.data());
+  }
+
+  return std::make_pair(pattern, nums);
+}
+
+[[nodiscard]] auto validate_pattern(std::string_view pattern, std::string_view line) -> bool
+{
+  if (pattern.size() != line.size()) { return false; }
+
+  for (auto pit{pattern.begin()}, lit{line.begin()}; pit != pattern.end(); ++pit, ++lit) {
+    if (*pit != '?' && *pit != *lit) { return false; }
+  }
+
+  return true;
+}
+
+void generate_pattern(std::string start, UIntVec::const_iterator it, UIntVec::const_iterator end,
+                      std::string_view pattern, UInt& count)
+{
+  start += std::string(*it++, '#');
+
+  if (it == end) {
+    if (start.size() <= pattern.size()) {
+      start.resize(pattern.size(), '.');
+      count += validate_pattern(pattern, start) ? 1 : 0;
+    }
+    return;
+  }
+
+  while (start.size() < pattern.size()) {
+    start += '.';
+    generate_pattern(start, it, end, pattern, count);
+  }
+}
+
+auto valid_sequences(std::string_view pattern, UIntVec const& nums) -> UInt
+{
+  UInt count{0};
+  std::string start;
+  while (start.size() < pattern.size()) {
+    generate_pattern(start, nums.begin(), nums.end(), pattern, count);
+    start += '.';
+  }
+
+  return count;
+}
+
+auto main() -> int try {
+  std::string line;
+  UInt count{0};
+
+  while (std::getline(std::cin, line)) {
+    auto [pattern, nums] = split(line);
+    UInt line_count{0};
+    line_count += valid_sequences(pattern, nums);
+    std::cout << line << ": " << line_count << '\n';
+    count += line_count;
+  }
+
+  std::cout << "Valid sequences: " << count << '\n';
+
+  return EXIT_SUCCESS;;
+}
+catch (...) {
+  std::cerr << "Uncaught exception.\n";
+  return EXIT_FAILURE;
+}