/source/library/Interlace/Collections/PriorityQueue.cs
C# | 206 lines | 135 code | 43 blank | 28 comment | 14 complexity | a49ccbf48b6170860e5e8dcb9bece5f9 MD5 | raw file
- #region Using Directives and Copyright Notice
-
- // Copyright (c) 2007-2010, Computer Consultancy Pty Ltd
- // All rights reserved.
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are met:
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above copyright
- // notice, this list of conditions and the following disclaimer in the
- // documentation and/or other materials provided with the distribution.
- // * Neither the name of the Computer Consultancy Pty Ltd nor the
- // names of its contributors may be used to endorse or promote products
- // derived from this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- // ARE DISCLAIMED. IN NO EVENT SHALL COMPUTER CONSULTANCY PTY LTD BE LIABLE
- // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- // SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- // OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
- // DAMAGE.
-
- using System;
- using System.Collections.Generic;
- using System.Text;
-
- using Interlace.Mathematics;
-
- #endregion
-
- namespace Interlace.Collections
- {
- public class PriorityQueue<T> where T : IComparable
- {
- T[] _elements;
- int _elementsUsed;
-
- public PriorityQueue()
- : this(16)
- {
- }
-
- public PriorityQueue(int capacity)
- {
- _elements = new T[BitTricks.NextPowerOfTwo(capacity)];
- _elementsUsed = 0;
- }
-
- public int Capacity
- {
- get
- {
- return _elements.Length;
- }
-
- set
- {
- ReallocateToCapacity(value);
- }
- }
-
- void ReallocateToCapacity(int newCapacity)
- {
- if (newCapacity < _elementsUsed)
- {
- throw new ArgumentOutOfRangeException(
- "The capacity of a heap can not be less than the count.");
- }
-
- T[] newElements = new T[newCapacity];
- Array.Copy(_elements, newElements, _elementsUsed);
-
- _elements = newElements;
- }
-
- void EnsureThereIsCapacityForAdd()
- {
- if (_elementsUsed < Capacity) return;
-
- int roundedOldCapacity = BitTricks.NextPowerOfTwo(Capacity);
- int newCapacity = roundedOldCapacity * 2;
-
- ReallocateToCapacity(newCapacity);
- }
-
- public void TrimToSize()
- {
- Capacity = Count;
- }
-
- public int Count
- {
- get { return _elementsUsed; }
- }
-
- void Heapify(int initialRoot)
- {
- int root = initialRoot;
-
- while (true)
- {
- int left = 2 * root + 1;
- int right = 2 * root + 2;
-
- int smallest;
-
- smallest = left < _elementsUsed && _elements[left].CompareTo(_elements[root]) < 0 ? left : root;
- smallest = right < _elementsUsed && _elements[right].CompareTo(_elements[smallest]) < 0 ? right : smallest;
-
- if (smallest == root) break;
-
- T temporary = _elements[root];
- _elements[root] = _elements[smallest];
- _elements[smallest] = temporary;
-
- root = smallest;
- }
- }
-
- public T Peek()
- {
- if (_elementsUsed < 1) throw new InvalidOperationException(
- "Elements can not be peeked at from an empty queue.");
-
- return _elements[0];
- }
-
- public T Dequeue()
- {
- if (_elementsUsed < 1) throw new InvalidOperationException(
- "Elements can not be dequeued from an empty queue.");
-
- T element = _elements[0];
- _elements[0] = _elements[_elementsUsed - 1];
- _elementsUsed--;
-
- // Avoid keeping references in the unused array slots for the garbage collector:
- _elements[_elementsUsed] = default(T);
-
- Heapify(0);
-
- return element;
- }
-
- public void Enqueue(T element)
- {
- EnsureThereIsCapacityForAdd();
-
- // Add the element at the end, assuming for now that it is the largest:
- _elements[_elementsUsed] = element;
- _elementsUsed++;
-
- int i = _elementsUsed - 1;
-
- // Pretend to increase the element to the real value, and let it bubble up:
- while (i > 0 && _elements[(i - 1) / 2].CompareTo(_elements[i]) > 0)
- {
- T temporary = _elements[i];
- _elements[i] = _elements[(i - 1) / 2];
- _elements[(i - 1) / 2] = temporary;
-
- i = (i - 1) / 2;
- }
- }
-
- public bool Remove(T element)
- {
- for (int i = 0; i < _elementsUsed; i++)
- {
- if (object.Equals(element, _elements[i]))
- {
- RemoveAt(i);
-
- return true;
- }
- }
-
- return false;
- }
-
- void RemoveAt(int i)
- {
- while (i > 0)
- {
- T temporary = _elements[i];
- _elements[i] = _elements[i / 2];
- _elements[(i - 1) / 2] = temporary;
-
- i = (i - 1) / 2;
- }
-
- Dequeue();
- }
-
- public void Clear()
- {
- _elementsUsed = 0;
- }
- }
- }