Files
advent-of-code/2023/puzzle-12-01.cc

94 lines
2.2 KiB
C++

#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;
}