Created
July 31, 2014 05:17
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Sparse set
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| #pragma once | |
| // Using Uninitialized Memory for Fun and Profit | |
| // http://research.swtch.com/sparse | |
| #include <vector> | |
| class SparseSet | |
| { | |
| private: | |
| size_t n_; | |
| std::vector<uint32_t> dense_, sparse_; | |
| public: | |
| SparseSet(size_t capacity = 1453689) | |
| : n_(0), dense_(capacity), sparse_(capacity) | |
| {} | |
| ~SparseSet() {} | |
| bool empty() const { return n_ == 0; } | |
| uint32_t back() const { return dense_[n_-1]; } | |
| void clear() { n_ = 0; } | |
| using iterator = std::vector<uint32_t>::iterator; | |
| using const_iterator = std::vector<uint32_t>::const_iterator; | |
| iterator begin() { return dense_.begin(); } | |
| iterator end() { return dense_.begin() + n_; } | |
| const_iterator begin() const { return dense_.begin(); } | |
| const_iterator end() const { return dense_.begin() + n_; } | |
| bool has(uint32_t i) const { | |
| if (i >= dense_.size()) | |
| return false; | |
| auto x = sparse_[i]; | |
| return x < n_ && dense_[x] == i; | |
| } | |
| void grow(size_t n) { | |
| n = std::max(n, dense_.size()) * 2; | |
| dense_.resize(n); | |
| sparse_.resize(n); | |
| } | |
| void insert(uint32_t i) { | |
| if (has(i)) return; | |
| if (i >= dense_.size()) grow(i); | |
| dense_[n_] = i; | |
| sparse_[i] = n_; | |
| ++n_; | |
| } | |
| void remove(uint32_t i) { | |
| if (!has(i)) return; | |
| uint32_t j = dense_[n_-1]; | |
| dense_[sparse_[i]] = j; | |
| sparse_[j] = sparse_[i]; | |
| --n_; | |
| } | |
| }; |
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