111 lines
2.8 KiB
C#
111 lines
2.8 KiB
C#
//
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// PriorityQueue.cs
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//
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// Authors:
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// Alexander Chebaturkin (chebaturkin@gmail.com)
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//
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// Copyright (C) 2011 Alexander Chebaturkin
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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using System;
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using System.Collections.Generic;
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namespace Mono.CodeContracts.Static.DataStructures {
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class PriorityQueue<T> {
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private readonly Comparison<T> comparison;
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private readonly List<T> values;
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public PriorityQueue (Comparison<T> compare)
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{
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this.comparison = compare;
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this.values = new List<T> ();
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this.values.Add (default(T)); //fake cell for start from 1
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}
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public int Count
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{
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get { return this.values.Count - 1; }
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}
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public T Peek ()
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{
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if (Count == 0)
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return default(T);
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return this.values [1];
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}
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public T Dequeue ()
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{
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if (Count == 0)
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return default(T);
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T res = this.values [1];
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this.values [1] = this.values [this.values.Count - 1];
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this.values.RemoveAt (this.values.Count - 1);
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BubbleDown (1);
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return res;
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}
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public void Enqueue (T item)
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{
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this.values.Add (item);
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BubbleUp (this.values.Count - 1);
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}
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private void BubbleDown (int i)
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{
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int l = i << 1;
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int r = (i << 1) + 1;
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int min = i;
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if (l < this.values.Count && this.comparison (this.values [l], this.values [i]) < 0)
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min = l;
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if (r < this.values.Count && this.comparison (this.values [r], this.values [min]) < 0)
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min = r;
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if (min != i) {
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T tmp = this.values [min];
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this.values [min] = this.values [i];
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this.values [i] = tmp;
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BubbleDown (min);
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}
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}
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private void BubbleUp (int i)
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{
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int c = i;
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while (c/2 != 0 &&
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this.comparison (this.values [c >> 1], this.values [c]) > 0) {
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T tmp = this.values [c >> 1];
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this.values [c >> 1] = this.values [c];
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this.values [c] = tmp;
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c >>= 1;
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}
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}
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}
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}
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