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#include <filesystem>
#include <fstream>
#include <iostream>
#include <map>
#include <sstream>
#include <string>
#include <vector>
// see: https://www.redblobgames.com/grids/hexagons/
using namespace std;
namespace {
string
read_file(const filesystem::path& filename)
{
ifstream file{ filename };
string line;
getline(file, line);
return line;
}
vector<string>
split(const string& line)
{
stringstream strm{ line };
vector<string> data;
for ( string word; getline(strm, word, ','); ) {
data.emplace_back(word);
}
return data;
}
void
part1(const vector<string>& steps)
{
// string => (q, s, r)
map<string, tuple<int, int, int>> dirs{
{ "n", { 0, 1, -1 } },
{ "nw", { -1, 1, 0 } },
{ "sw", { -1, 0, 1 } },
{ "s", { 0, -1, 1 } },
{ "se", { 1, -1, 0 } },
{ "ne", { 1, 0, -1 } }
};
tuple<int, int, int> current = { 0, 0, 0 };
for ( const auto& step: steps ) {
const auto [dq, ds, dr] = dirs.at(step);
get<0>(current) += dq;
get<1>(current) += ds;
get<2>(current) += dr;
}
auto dist = (abs(get<0>(current)) + abs(get<1>(current)) + abs(get<2>(current))) / 2;
cout << "Part1: " << dist << '\n';
}
void
part2(const vector<string>& steps)
{
// string => (q, s, r)
map<string, tuple<int, int, int>> dirs{
{ "n", { 0, 1, -1 } },
{ "nw", { -1, 1, 0 } },
{ "sw", { -1, 0, 1 } },
{ "s", { 0, -1, 1 } },
{ "se", { 1, -1, 0 } },
{ "ne", { 1, 0, -1 } }
};
int max_dist = 0;
tuple<int, int, int> current = { 0, 0, 0 };
for ( const auto& step: steps ) {
const auto [dq, ds, dr] = dirs.at(step);
get<0>(current) += dq;
get<1>(current) += ds;
get<2>(current) += dr;
auto dist = (abs(get<0>(current)) + abs(get<1>(current)) + abs(get<2>(current))) / 2;
max_dist = max(max_dist, dist);
}
cout << "Part2: " << max_dist << '\n';
}
} // namespace
int
main()
{
auto line = read_file("data/day11.txt");
auto steps = split(line);
part1(steps);
part2(steps);
}
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