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#include <fstream>
#include <iostream>
#include <map>
#include <regex>
#include <string>
#include <vector>
using namespace std;
string
read_file(string_view filename)
{
fstream input{ filename };
return { istreambuf_iterator<char>{ input }, istreambuf_iterator<char>{} };
}
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);
}
if ( pos_start != line.size() ) {
res.emplace_back(line.substr(pos_start));
}
return res;
}
void
part1()
{
const auto input = split(read_file("data/day19.txt"), "\n\n");
const auto rules_string = split(input[0], "\n");
const auto parts = split(input[1], "\n");
const regex rules_pattern{ R"((.*)\{(.*),(.*)\})" };
const regex sub_rules_pattern{ R"((.)(.)(\d*):(.*))" };
map<string, tuple<vector<tuple<string, string, long, string>>, string>> rules;
for ( const auto& rule: rules_string ) {
smatch smatch;
if ( regex_search(rule, smatch, rules_pattern) ) {
string rule_name = smatch[1];
string default_dest = smatch[3];
vector<tuple<string, string, long, string>> foo;
for ( const auto& sub_rule: split(smatch[2].str(), ",") ) {
std::smatch smatch2;
if ( regex_search(sub_rule, smatch2, sub_rules_pattern) ) {
foo.emplace_back(smatch2[1], smatch2[2], stol(smatch2[3]), smatch2[4]);
}
}
rules[rule_name] = make_tuple(foo, default_dest);
}
}
long sum = 0;
const regex parts_pattern{ R"(\{x=(\d*),m=(\d*),a=(\d*),s=(\d*)\})" };
for ( const auto& part: parts ) {
smatch smatch;
if ( regex_search(part, smatch, parts_pattern) ) {
const auto xval = stol(smatch[1]);
const auto mval = stol(smatch[2]);
const auto aval = stol(smatch[3]);
const auto sval = stol(smatch[4]);
string rule = "in";
while ( rule != "A" && rule != "R" ) {
auto sub_rules = get<0>(rules[rule]);
auto next_rule = get<1>(rules[rule]);
for ( auto sub_rule: sub_rules ) {
const auto field = get<0>(sub_rule);
const auto cmp = get<1>(sub_rule);
const auto value = get<2>(sub_rule);
if ( field == "x" && ((cmp == ">" && xval > value) || (cmp == "<" && xval < value)) ) {
next_rule = get<3>(sub_rule);
break;
}
if ( field == "m" && ((cmp == ">" && mval > value) || (cmp == "<" && mval < value)) ) {
next_rule = get<3>(sub_rule);
break;
}
if ( field == "a" && ((cmp == ">" && aval > value) || (cmp == "<" && aval < value)) ) {
next_rule = get<3>(sub_rule);
break;
}
if ( field == "s" && ((cmp == ">" && sval > value) || (cmp == "<" && sval < value)) ) {
next_rule = get<3>(sub_rule);
break;
}
}
rule = next_rule;
}
if (rule == "A") {
sum += xval;
sum += mval;
sum += aval;
sum += sval;
}
}
}
cout << sum << endl;
}
int
main()
{
part1();
}
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