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/******************************************************************************************[Heap.h] |
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Copyright (c) 2003-2006, Niklas Een, Niklas Sorensson |
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Copyright (c) 2007-2010, Niklas Sorensson |
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software and |
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associated documentation files (the "Software"), to deal in the Software without restriction, |
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including without limitation the rights to use, copy, modify, merge, publish, distribute, |
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sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is |
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furnished to do so, subject to the following conditions: |
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The above copyright notice and this permission notice shall be included in all copies or |
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substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT |
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NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, |
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DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT |
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OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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**************************************************************************************************/ |
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#ifndef Minisat_Heap_h |
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#define Minisat_Heap_h |
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#include "base/check.h" |
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#include "prop/minisat/mtl/Vec.h" |
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namespace cvc5 { |
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namespace Minisat { |
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//================================================================================================= |
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// A heap implementation with support for decrease/increase key. |
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template<class Comp> |
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class Heap { |
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Comp lt; // The heap is a minimum-heap with respect to this comparator |
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vec<int> heap; // Heap of integers |
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vec<int> indices; // Each integers position (index) in the Heap |
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// Index "traversal" functions |
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static inline int left (int i) { return i*2+1; } |
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static inline int right (int i) { return (i+1)*2; } |
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static inline int parent(int i) { return (i-1) >> 1; } |
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void percolateUp(int i) |
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{ |
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int x = heap[i]; |
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int p = parent(i); |
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while (i != 0 && lt(x, heap[p])){ |
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heap[i] = heap[p]; |
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indices[heap[p]] = i; |
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i = p; |
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p = parent(p); |
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} |
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heap [i] = x; |
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indices[x] = i; |
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} |
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void percolateDown(int i) |
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{ |
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int x = heap[i]; |
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while (left(i) < heap.size()){ |
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int child = right(i) < heap.size() && lt(heap[right(i)], heap[left(i)]) ? right(i) : left(i); |
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if (!lt(heap[child], x)) break; |
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heap[i] = heap[child]; |
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indices[heap[i]] = i; |
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i = child; |
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} |
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heap [i] = x; |
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indices[x] = i; |
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} |
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public: |
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Heap(const Comp& c) : lt(c) { } |
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int size () const { return heap.size(); } |
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bool empty () const { return heap.size() == 0; } |
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bool inHeap (int n) const { return n < indices.size() && indices[n] >= 0; } |
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int operator[](int index) const |
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{ |
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Assert(index < heap.size()); |
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return heap[index]; |
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} |
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void decrease(int n) |
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{ |
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Assert(inHeap(n)); |
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percolateUp(indices[n]); |
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} |
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void increase(int n) |
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{ |
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Assert(inHeap(n)); |
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percolateDown(indices[n]); |
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} |
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// Safe variant of insert/decrease/increase: |
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void update(int n) |
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{ |
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if (!inHeap(n)) |
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insert(n); |
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else { |
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percolateUp(indices[n]); |
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percolateDown(indices[n]); } |
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} |
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void insert(int n) |
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{ |
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indices.growTo(n+1, -1); |
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Assert(!inHeap(n)); |
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indices[n] = heap.size(); |
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heap.push(n); |
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percolateUp(indices[n]); |
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} |
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int removeMin() |
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{ |
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int x = heap[0]; |
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heap[0] = heap.last(); |
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indices[heap[0]] = 0; |
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indices[x] = -1; |
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heap.pop(); |
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if (heap.size() > 1) percolateDown(0); |
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return x; |
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} |
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// Rebuild the heap from scratch, using the elements in 'ns': |
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void build(vec<int>& ns) { |
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for (int i = 0; i < heap.size(); i++) |
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indices[heap[i]] = -1; |
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heap.clear(); |
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for (int i = 0; i < ns.size(); i++){ |
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indices[ns[i]] = i; |
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heap.push(ns[i]); } |
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for (int i = heap.size() / 2 - 1; i >= 0; i--) |
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percolateDown(i); |
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} |
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void clear(bool dealloc = false) |
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{ |
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for (int i = 0; i < heap.size(); i++) |
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indices[heap[i]] = -1; |
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heap.clear(dealloc); |
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} |
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}; |
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//================================================================================================= |
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} |
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} // namespace cvc5 |
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#endif |