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#include <iostream>
#include <fstream>
#include <sstream>
#include <unordered_map>
#include <vector>
#include "util.h"
using Moves = std::vector<bool>;
using Map = std::unordered_map<int,std::pair<int,int>>;
constexpr char EQUAL[] = "=";
int encode(std::string str)
{
int res{};
for (unsigned char c : str)
{
if ('A' <= c and c <= 'Z')
{
res *= 1 + 'Z' - 'A';
res += c - 'A';
}
}
return res;
}
std::pair<Moves,Map> parse(const char* path)
{
Map map{};
Moves moves{};
std::ifstream input{ path };
if (input.is_open())
{
std::string line;
std::getline(input,line);
moves.resize(line.size());
std::transform(line.cbegin(), line.cend(),
moves.begin(), [](unsigned char c) { return c == 'L'; });
std::string from, tol, tor;
while (not std::getline(input,line).eof())
{
if (line.empty()) continue;
std::istringstream in{ line };
in >> from >> util::skip<EQUAL> >> tol >> tor;
map.insert({ encode(from), { encode(tol), encode(tor) } });
}
}
input.close();
return { std::move(moves), std::move(map) };
}
int main(int argc, char* argv[])
{
int answer{};
auto [moves, map] = parse(argv[1]);
for (int pos = encode("AAA");
pos != encode("ZZZ");
pos = moves[answer++ % moves.size()] ? map[pos].first : map[pos].second);
std::cout << answer << std::endl;
return 0;
}
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