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#include <filesystem>
#include <fstream>
#include <iostream>
#include <regex>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
namespace {
using Range = tuple<long, long>;
using Ranges = vector<Range>;
tuple<Ranges, vector<long>>
read_file(const filesystem::path& filename)
{
static const regex range{ R"(^(\d+)-(\d+)$)" };
static const regex single{ R"(^(\d+)$)" };
ifstream file{ filename };
Ranges ranges;
vector<long> numbers;
for ( string line; getline(file, line); ) {
smatch match;
if ( regex_match(line, match, range) ) {
ranges.emplace_back(stol(match[1]), stol(match[2]));
}
else if ( regex_match(line, match, single) ) {
numbers.emplace_back(stol(match[1]));
}
}
return { ranges, numbers };
}
void
part1(const Ranges& ranges, const vector<long>& numbers)
{
long count = 0;
for ( const auto number: numbers ) {
for ( const auto [start, end]: ranges ) {
if ( start <= number && number <= end ) {
++count;
break;
}
}
}
cout << "Part 1: " << count << '\n';
}
void
part2(Ranges ranges)
{
ranges::sort(ranges);
Ranges merged;
merged.emplace_back(ranges[0]);
for ( size_t i = 1; i < ranges.size(); ++i ) {
auto& [last_start, last_end] = merged.back();
auto& [curr_start, curr_end] = ranges[i];
if ( last_end < curr_start ) {
merged.emplace_back(ranges[i]);
}
else if ( last_end < curr_end ) {
last_end = curr_end;
}
}
long count = 0;
for ( const auto [start, end]: merged ) {
count += end - start + 1;
}
cout << "Part 2: " << count << '\n';
}
} // namespace
int
main()
{
const auto [ranges, numbers] = read_file("data/day05.txt");
part1(ranges, numbers);
part2(ranges);
}
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