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#include <filesystem>
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
namespace {
class Machine {
public:
Machine(unsigned long dest, const vector<unsigned long>& buttons)
: dest_{ dest }
, buttons_{ buttons }
{
}
void push(size_t button)
{
curr_ ^= buttons_.at(button);
++pushes_;
}
[[nodiscard]]
bool test() const
{
return curr_ == dest_;
}
void reset()
{
curr_ = 0;
pushes_ = 0;
}
[[nodiscard]]
unsigned long button_count() const
{
return buttons_.size();
}
[[nodiscard]]
unsigned long get_pushes() const
{
return pushes_;
}
private:
unsigned long dest_;
unsigned long curr_{ 0 };
unsigned long pushes_{ 0 };
vector<unsigned long> buttons_;
};
vector<string>
split(const string& str, const string& delims)
{
vector<string> result;
size_t start = str.find_first_not_of(delims);
while ( start != string::npos ) {
size_t end = str.find_first_of(delims, start);
if ( end == string::npos ) {
// letzter Teil
result.push_back(str.substr(start));
break;
}
result.push_back(str.substr(start, end - start));
start = str.find_first_not_of(delims, end);
}
return result;
}
vector<unsigned long>
split(const string& str)
{
stringstream strm{ str };
vector<unsigned long> values;
for ( string part; getline(strm, part, ','); ) {
values.emplace_back(stoul(part));
}
return values;
}
unsigned long
from_pattern(string pattern)
{
unsigned long value = 0;
ranges::reverse(pattern);
for ( const char chr: pattern ) {
value <<= 1UL;
value |= (chr == '#') ? 1U : 0U;
}
return value;
}
unsigned long
from_button_string(const string& pattern)
{
unsigned long value = 0;
for ( const auto pos: split(pattern) ) {
value |= (1UL << pos);
}
return value;
}
vector<Machine>
read_file(const filesystem::path& filename)
{
ifstream file{ filename };
vector<Machine> machines;
for ( string line; getline(file, line); ) {
const auto parts = split(line, "[] (){}");
const auto dest = from_pattern(parts[0]);
vector<unsigned long> buttons;
for ( size_t i = 1; i < parts.size() - 1; ++i ) {
buttons.emplace_back(from_button_string(parts[i]));
}
machines.emplace_back(dest, buttons);
}
return machines;
}
unsigned long
simulate(Machine machine)
{
auto min_so_far = numeric_limits<unsigned long>::max();
const auto button_count = machine.button_count();
for ( unsigned long i = 0; i != (1UL << button_count); ++i ) {
machine.reset();
for ( unsigned long button = 0; button != button_count; ++button ) {
if ( (i & (1UL << button)) != 0 ) {
machine.push(button);
}
}
if ( machine.test() ) {
min_so_far = min(min_so_far, machine.get_pushes());
}
}
return min_so_far;
}
void
part1(const vector<Machine>& machines)
{
unsigned long count = 0;
for ( const auto& machine: machines ) {
count += simulate(machine);
}
cout << "Part 1: " << count << '\n';
}
} // namespace
int
main()
{
auto machines = read_file("data/day10.txt");
part1(machines);
}
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