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#include <fstream>
#include <iostream>
#include <map>
#include <numeric>
#include <set>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
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<set<string>, vector<string>>
read_file(string_view filename)
{
fstream input{ filename };
vector<string> lines;
for ( string line; getline(input, line); ) {
lines.emplace_back(line);
}
const auto parts = split(lines[0], ", ");
return { { parts.begin(), parts.end() }, { lines.begin() + 2, lines.end() } };
}
void
part1(const tuple<set<string>, vector<string>>& data)
{
const auto& parts = get<0>(data);
const auto& lines = get<1>(data);
map<string, bool> cache;
function<bool(const string&)> match = [&](const string& line) {
if ( line.empty() ) {
return true;
}
if ( cache.contains(line) ) {
return cache.at(line);
}
for ( size_t i = 0; i != line.size(); ++i ) {
if ( parts.contains(line.substr(0, i + 1)) ) {
if ( match(line.substr(i + 1)) ) {
return cache[line] = true;
}
}
}
return cache[line] = false;
};
cout << ranges::count_if(lines, match) << endl;
}
void
part2(const tuple<set<string>, vector<string>>& data)
{
const auto& parts = get<0>(data);
const auto& lines = get<1>(data);
map<string, long> cache;
function<long(const string&)> match = [&](const string& line) -> long {
if ( line.empty() ) {
return 1;
}
if ( cache.contains(line) ) {
return cache.at(line);
}
long counter = 0;
for ( size_t i = 0; i != line.size(); ++i ) {
auto lhs = line.substr(0, i + 1);
auto rhs = line.substr(i + 1);
if ( parts.contains(lhs) ) {
counter += match(rhs);
}
}
return cache[line] = counter;
};
cout << accumulate(lines.begin(), lines.end(), 0L, [&](auto init, const auto& line) { return init + match(line); }) << endl;
}
int
main()
{
const auto data = read_file("data/day19.txt");
part1(data);
part2(data);
}
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