121 lines
3.0 KiB
C++
121 lines
3.0 KiB
C++
// Solutions to the Advent Of Code 2024.
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// Copyright (C) 2024 Stefan Müller
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//
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// This program is free software: you can redistribute it and/or modify it under
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// the terms of the GNU General Public License as published by the Free Software
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// Foundation, either version 3 of the License, or (at your option) any later
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// version.
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//
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along with
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// this program. If not, see <http://www.gnu.org/licenses/>.
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#include <aoc/PrintQueue.hpp>
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#include <algorithm>
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#include <sstream>
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#include <vector>
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PrintQueue::PrintQueue()
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: Solver{}, isProcessingOrderingRules_{ true }, pageNoMapIndex_{ 0 }, pageNoMap_(getMaxPageNo() + 1, -1),
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orderingRules_(getNPages(), getNPages())
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{
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orderingRules_.fill(false);
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}
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const std::string PrintQueue::getPuzzleName() const
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{
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return "Print Queue";
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}
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const int PrintQueue::getPuzzleDay() const
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{
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return 5;
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}
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void PrintQueue::processDataLine(const std::string& line)
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{
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if (isProcessingOrderingRules_)
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{
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if (line.empty())
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{
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isProcessingOrderingRules_ = false;
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}
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else
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{
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processOrderingRule(line);
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}
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}
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else
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{
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processUpdatePages(line);
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}
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}
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void PrintQueue::finish()
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{
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}
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constexpr int PrintQueue::getNPages()
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{
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return 49;
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}
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constexpr int PrintQueue::getMaxPageNo()
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{
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return 99;
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}
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size_t PrintQueue::getMapped(const int pageNo)
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{
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if (pageNoMap_[pageNo] < 0)
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{
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pageNoMap_[pageNo] = pageNoMapIndex_++;
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}
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return pageNoMap_[pageNo];
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}
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void PrintQueue::processOrderingRule(const std::string& line)
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{
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size_t pos{ line.find("|") };
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int before{ std::stoi(line.substr(0, pos)) };
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int after{ std::stoi(line.substr(pos + 1)) };
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orderingRules_[getMapped(before)][getMapped(after)] = true;
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}
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void PrintQueue::processUpdatePages(const std::string& line)
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{
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std::vector<int> pages{};
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std::istringstream stream{ line };
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std::string token;
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bool isCorrectOrder{ true };
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// We completely construct 'pages' for part 2, even if the ordering is not correct.
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while (std::getline(stream, token, ','))
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{
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int page = std::stoi(token);
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size_t i{ 0 };
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while (isCorrectOrder && i < pages.size())
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{
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isCorrectOrder = !orderingRules_[getMapped(page)][getMapped(pages[i])];
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i++;
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}
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pages.push_back(page);
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}
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if (isCorrectOrder)
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{
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part1 += pages[pages.size() / 2];
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}
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else
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{
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// This works because the input defines a complete ordering on the occurring
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// page numbers.
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std::sort(pages.begin(), pages.end(),
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[&](int const& a, int const& b) { return orderingRules_[getMapped(a)][getMapped(b)]; });
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part2 += pages[pages.size() / 2];
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}
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}
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