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#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
using pattern_type = vector<string>;
vector<string>
split(string_view line, string_view delimiter)
{
size_t pos_start = 0;
size_t pos_end = 0;
vector<string> res;
while ( (pos_end = line.find(delimiter, pos_start)) != std::string::npos ) {
auto token = line.substr(pos_start, pos_end - pos_start);
pos_start = pos_end + delimiter.length();
res.emplace_back(token);
}
res.emplace_back(line.substr(pos_start));
return res;
}
tuple<vector<pattern_type>, vector<pattern_type>>
read_file(string_view filename)
{
fstream input{ filename };
const auto patterns{ split(string{ istreambuf_iterator<char>{ input }, {} }, "\n\n") };
vector<pattern_type> keys;
vector<pattern_type> locks;
for ( const auto& pattern: patterns ) {
const pattern_type& lines = split(pattern, "\n");
if ( lines[0] == "#####" && lines[6] == "....." ) {
locks.push_back(lines);
}
else if ( lines[0] == "....." && lines[6] == "#####" ) {
keys.push_back(lines);
}
}
return { keys, locks };
}
bool
fits(const pattern_type& key, const pattern_type& lock)
{
for ( size_t row = 0; row != key.size(); ++row ) {
for ( size_t col = 0; col != key[row].size(); ++col ) {
if ( key[row][col] == '#' && lock[row][col] == '#' ) {
return false;
}
}
}
return true;
}
void
part1(const tuple<vector<pattern_type>, vector<pattern_type>>& data)
{
const auto [keys, locks] = data;
long count = 0;
for ( const auto& key: keys ) {
for ( const auto& lock: locks ) {
if ( fits(key, lock) ) {
++count;
}
}
}
cout << count << endl;
}
int
main()
{
const auto data = read_file("data/day25.txt");
part1(data);
}
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