149 lines
4.6 KiB
C
149 lines
4.6 KiB
C
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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 "mtl/Vec.h"
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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 { assert(index < heap.size()); return heap[index]; }
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void decrease (int n) { assert(inHeap(n)); percolateUp (indices[n]); }
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void increase (int n) { assert(inHeap(n)); percolateDown(indices[n]); }
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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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#endif
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