49 lines
1.4 KiB
C++
49 lines
1.4 KiB
C++
// Copyright 2010-2025 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef ORTOOLS_UTIL_CACHED_LOG_H_
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#define ORTOOLS_UTIL_CACHED_LOG_H_
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#include <cstdint>
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#include <vector>
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namespace operations_research {
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// This class is used when manipulating search space estimations. It
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// provides fast access to log of a domain size.
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// Future Extensions:
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// - Sum of log on an array.
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// - Sum of log on an array with callback.
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class CachedLog {
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public:
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CachedLog();
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// This type is neither copyable nor movable.
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CachedLog(const CachedLog&) = delete;
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CachedLog& operator=(const CachedLog&) = delete;
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~CachedLog();
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// This method can only be called once, and with a cache_size > 0.
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void Init(int cache_size);
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// Returns the log2 of 'input'.
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double Log2(int64_t input) const;
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private:
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std::vector<double> cache_;
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};
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} // namespace operations_research
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#endif // ORTOOLS_UTIL_CACHED_LOG_H_
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