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#include <filesystem>
#include <fstream>
#include <iostream>
#include <tuple>
#include <vector>
using namespace std;
namespace {
vector<tuple<unsigned long, unsigned long>>
read_file(const filesystem::path& filename)
{
ifstream file{ filename };
unsigned long depth = 0;
unsigned long range = 0;
char colon = 0;
vector<tuple<unsigned long, unsigned long>> data;
while ( file >> depth >> colon >> range ) {
data.emplace_back(depth, range);
}
return data;
}
template<typename T>
T
get_pos(T depth, T range, T time)
{
const auto period = 2 * (range - 1);
const auto remainder = (depth + time) % period;
return remainder < range ? remainder : period - remainder;
}
void
part1(const vector<tuple<unsigned long, unsigned long>>& data)
{
unsigned long sum = 0;
for ( const auto [depth, range]: data ) {
if ( get_pos(depth, range, 0UL) == 0 ) {
sum += depth * range;
}
}
cout << "Part1: " << sum << '\n';
}
void
part2(const vector<tuple<unsigned long, unsigned long>>& data)
{
for ( unsigned long delay = 0;; ++delay ) {
bool pass = true;
for ( const auto [depth, range]: data ) {
if ( get_pos(depth, range, delay) == 0 ) {
pass = false;
break;
}
}
if ( pass ) {
cout << "Part2: " << delay << '\n';
return;
}
}
}
} // namespace
int
main()
{
auto data = read_file("data/day13.txt");
part1(data);
part2(data);
}
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