45 lines
2.0 KiB
C++
45 lines
2.0 KiB
C++
// Solutions to the Advent Of Code 2024.
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// Copyright (C) 2025 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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#pragma once
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#include <map>
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#include <string>
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#include <vector>
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class LinenTowelPatterns
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{
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public:
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LinenTowelPatterns();
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void add(const std::string& towelPattern);
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int64_t countArrangements(const std::string& design);
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private:
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/// <summary>
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/// Tree data structure of all valid towel patterns. Each element is a vertex in the tree and represents a stripe in
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/// a towel pattern given by 's = i mod n', where 's' is the unique index offset of the stripe as defined in
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/// 'stripes_', 'i' is the index of the element, and 'n' is the number of stripes, i.e. the 'stripes_.size()'.
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/// The first value of each element indicates the next set of stripes to continue the pattern accumulated by
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/// following the path in the tree. If it is 0, this element is a leaf, and the pattern does not continue.
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/// Otherwise, it is the index of its first of 'n' children, which are contiguous in the vector. The second value of
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/// each element indicates whether there is a towel with the pattern ending at this element.
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/// </summary>
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std::vector<std::pair<size_t, bool>> patterns_;
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/// <summary>
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/// Maps stripes (represented by chars) to an index offset in the tree of towel patterns.
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/// </summary>
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std::map<char, size_t> stripes_;
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void addBranch();
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};
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