Files
advent-of-code/2022/puzzle-13-02.cc

117 lines
2.8 KiB
C++

//
// Created by Matthew Gretton-Dann on 09/12/2022.
//
#include <array>
#include <iostream>
#include <set>
#include <string>
#include <utility>
using Int = std::int64_t;
using UInt = std::uint64_t;
struct Ordering
{
auto operator()(std::string const& left, std::string const& right) const noexcept -> bool
{
auto left_it{left.begin()};
auto right_it{right.begin()};
UInt left_depth{0};
UInt right_depth{0};
while (left_it != left.end() && right_it != right.end()) {
while (left_it != left.end() && *left_it == '[') {
++left_depth;
++left_it;
}
while (right_it != right.end() && *right_it == '[') {
++right_depth;
++right_it;
}
std::size_t left_pos{0};
std::size_t right_pos{0};
UInt left_num{0};
UInt right_num{0};
if (left_it != left.end() && std::isdigit(*left_it) != 0) {
left_num = std::stoull(left.substr(left_it - left.begin()), &left_pos);
}
if (right_it != right.end() && std::isdigit(*right_it) != 0) {
right_num = std::stoull(right.substr(right_it - right.begin()), &right_pos);
}
left_it += static_cast<std::string::difference_type>(left_pos);
right_it += static_cast<std::string::difference_type>(right_pos);
if (right_pos == 0) {
if (left_pos != 0) {
return false;
}
if (left_depth < right_depth) {
return true;
}
if (right_depth > left_depth) {
return false;
}
}
else if (left_pos == 0) {
return true;
}
if (right_num < left_num) {
return false;
}
if (left_num < right_num) {
return true;
}
while (left_it != left.end() && *left_it == ']') {
--left_depth;
++left_it;
}
while (right_it != right.end() && *right_it == ']') {
--right_depth;
++right_it;
}
if (left_depth != right_depth) {
return left_depth < right_depth;
}
if (left_it != left.end() && *left_it == ',') {
++left_it;
}
if (right_it != left.end() && *right_it == ',') {
++right_it;
}
}
return left_it == left.end();
}
};
auto main() -> int
{
std::string line;
std::set<std::string, Ordering> strings;
strings.insert("[[2]]");
strings.insert("[[6]]");
while (std::getline(std::cin, line)) {
if (line.empty()) {
continue;
}
strings.insert(line);
}
UInt dist2{0};
UInt dist6{0};
UInt idx{1};
for (auto const& s : strings) {
if (Ordering{}(s, "[[2]]")) {
++dist2;
++dist6;
}
else if (Ordering{}(s, "[[6]]")) {
++dist6;
}
std::cout << idx++ << ": " << s << '\n';
}
std::cout << "Score: " << dist2 << " * " << dist6 << " = " << dist2 * dist6 << '\n';
return 0;
}