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#include <array>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <map>
#include <regex>
#include <string>
#include <vector>
using namespace std;
namespace {
using Region = tuple<long, long, array<long, 6>>;
tuple<map<long, long>, vector<Region>>
read_file(const filesystem::path& filename)
{
ifstream file{ filename };
vector<string> lines;
for ( string line; getline(file, line); ) {
lines.emplace_back(line);
}
map<long, long> areas;
size_t idx = 0;
for ( ;; idx += 5 ) {
if ( lines.at(idx).at(1) != ':' ) {
break;
}
const long num = lines.at(idx).at(0) - '0';
long count = 0;
for ( size_t j = idx + 1; j != idx + 4; ++j ) {
count += ranges::count(lines.at(j), '#');
}
areas[num] = count;
}
vector<Region> regions;
for ( ; idx != lines.size(); ++idx ) {
static const regex rgx(R"(^(\d+)x(\d+):\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)$)");
smatch match;
if ( !regex_match(lines.at(idx), match, rgx) ) {
continue;
}
regions.emplace_back(
stol(match[1]), // width
stol(match[2]), // height
array<long, 6>{
stol(match[3]),
stol(match[4]),
stol(match[5]),
stol(match[6]),
stol(match[7]),
stol(match[8]) } // counts
);
}
return { areas, regions };
}
void
part1(const map<long, long>& areas, const vector<Region>& regions)
{
const auto result = ranges::count_if(regions, [&](const auto& region) {
const auto& [width, height, counts] = region;
long required = 0;
for ( size_t i = 0; i != counts.size(); ++i ) {
required += counts.at(i) * areas.at(static_cast<long>(i));
}
return required < width * height;
});
cout << "Part 1: " << result << '\n';
}
} // namespace
int
main()
{
const auto [areas, regions] = read_file("data/day12.txt");
part1(areas, regions);
}
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