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#include <algorithm>
#include <cstddef>
#include <fstream>
#include <iostream>
#include <map>
#include <set>
#include <sstream>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
auto
split(const string& line, char sep = ' ')
{
vector<string> parts;
stringstream input{ line };
for ( string part; getline(input, part, sep); ) {
parts.emplace_back(part);
}
return parts;
}
tuple<string, vector<tuple<string, string>>>
read_file(string_view filename)
{
fstream input{ filename };
vector<tuple<string, string>> table;
string molecule;
for ( string line; getline(input, line); ) {
auto parts = split(line);
if ( parts.size() == 3 && parts[1] == "=>" ) {
table.emplace_back(parts[0], parts[2]);
}
if ( parts.size() == 1 ) {
molecule = parts[0];
}
}
return { molecule, table };
}
void
part1(const string& molecule, const vector<tuple<string, string>>& table)
{
set<string> set;
for ( const auto& [left, right]: table ) {
size_t pos = 0;
while ( true ) {
string temp = molecule;
pos = temp.find(left, pos);
if ( pos == string::npos ) {
break;
}
temp.replace(pos, left.length(), right);
++pos;
set.insert(temp);
}
}
cout << set.size() << endl;
}
size_t
replace_all(string& str, string_view replace, string_view replaceWith)
{
size_t count = 0;
auto pos = str.find(replace);
while ( pos != string::npos ) {
str.replace(pos, replace.size(), replaceWith);
++count;
pos = str.find(replace, pos + replace.size());
}
return count;
}
void
part2(string molecule)
{
replace_all(molecule, "Rn", "(");
replace_all(molecule, "Y", ",");
replace_all(molecule, "Ar", ")");
molecule.erase(remove_if(molecule.begin(), molecule.end(), [](auto chr) -> bool {
return islower(chr);
}),
molecule.end());
transform(molecule.begin(), molecule.end(), molecule.begin(), [](auto chr) {
return isalpha(chr) ? 'X' : chr;
});
size_t count = 0;
while ( molecule != "X" ) {
for ( const auto& item: { "XX", "X(X)", "X(X,X)", "X(X,X,X)" } ) {
count += replace_all(molecule, item, "X");
}
}
cout << count << endl;
}
int
main()
{
const auto [molecule, table] = read_file("data/day19.txt");
part1(molecule, table);
part2(molecule);
}
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