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#include <fstream>
#include <iostream>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
vector<long>
split(const string& line, char sep = ',')
{
vector<long> parts;
stringstream input{ line };
for ( string part; getline(input, part, sep); ) {
parts.emplace_back(stol(part));
}
return parts;
}
tuple<vector<tuple<long, long>>, vector<vector<long>>>
read_file(string_view filename)
{
fstream input{ filename };
vector<tuple<long, long>> rules;
for ( string line; getline(input, line); ) {
if ( line.empty() ) {
break;
}
long lhs = 0;
long rhs = 0;
sscanf(line.c_str(), "%ld|%ld", &lhs, &rhs); // NOLINT
rules.emplace_back(lhs, rhs);
}
vector<vector<long>> pages;
for ( string line; getline(input, line); ) {
pages.emplace_back(split(line));
}
return { rules, pages };
}
bool
is_valid(const vector<tuple<long, long>>& rules, const vector<long>& page)
{
set<long> processed;
bool invalid = false;
for ( const auto& num: page ) {
processed.emplace(num);
auto pred = [num](const tuple<long, long>& rule) {
return get<0>(rule) == num;
};
for ( auto it = find_if(rules.begin(), rules.end(), pred); it != rules.end(); it = find_if(it + 1, rules.end(), pred) ) {
const auto foo = get<1>(*it);
if ( processed.contains(foo) ) {
invalid = true;
}
}
}
return !invalid;
}
void
part1(const vector<tuple<long, long>>& rules, const vector<vector<long>>& pages)
{
long sum = 0;
for ( const auto& page: pages ) {
if ( is_valid(rules, page) ) {
sum += page.at(page.size() / 2);
}
}
cout << sum << endl;
}
void
part2(const vector<tuple<long, long>>& rules, const vector<vector<long>>& pages)
{
long sum = 0;
for ( auto page: pages ) {
if ( !is_valid(rules, page) ) {
ranges::sort(page, [&](auto lhs, auto rhs) -> bool {
return ranges::find(rules, make_tuple(lhs, rhs)) != rules.end();
});
sum += page.at(page.size() / 2);
}
}
cout << sum << endl;
}
int
main()
{
auto [rules, pages] = read_file("data/day05.txt");
part1(rules, pages);
part2(rules, pages);
}
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