File size: 4,561 Bytes
b1b3bae |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 |
/// ------------------------------------------------------
/// RandomOps - (Pseudo) Random Number Generator For C#
/// Copyright (C) 2003-2010 Magnus Erik Hvass Pedersen.
/// Please see the file license.txt for license details.
/// RandomOps on the internet: http://www.Hvass-Labs.org/
/// ------------------------------------------------------
using System.Diagnostics;
namespace RandomOps
{
/// <summary>
/// A set of integers enumerated from zero and upwards that
/// can be drawn at random. Creation or resetting takes time
/// O(n) where n is the size of the set, and drawing a random
/// element from the set takes constant time O(1). Not thread-safe.
/// </summary>
public class Set
{
#region Public properties.
/// <summary>
/// Number of elements available for drawing.
/// </summary>
public int Size
{
get;
private set;
}
/// <summary>
/// Maximum number of elements in the set.
/// </summary>
public int Capacity
{
get;
private set;
}
#endregion
#region Constructor.
/// <summary>
/// Creates but does not initialize the random set.
/// </summary>
/// <param name="rand">RNG object to use for random drawing.</param>
/// <param name="capacity">Number of elements in the set.</param>
public Set(Random rand, int capacity)
{
Rand = rand;
Elms = new int[capacity];
Capacity = capacity;
Size = 0;
}
#endregion
#region Internal variables.
/// <summary>
/// The RNG used for drawing elements from the set.
/// </summary>
Random Rand;
/// <summary>
/// Array used for holding the elements of the set.
/// </summary>
int[] Elms;
#endregion
#region Internal methods.
/// <summary>
/// Swap the i'th and j'th elements of the internal array.
/// </summary>
void Swap(int i, int j)
{
Debug.Assert(i >= 0 && i < Capacity);
Debug.Assert(j >= 0 && j < Capacity);
int temp = Elms[i];
Elms[i] = Elms[j];
Elms[j] = temp;
}
/// <summary>
/// Remove an element from the set.
/// </summary>
/// <param name="index">Position of element to be removed.</param>
void Remove(int index)
{
// Various assumptions.
Debug.Assert(Size >= 1);
Debug.Assert(index >= 0 && index < Size);
// Decrease the number of elements in the set.
Size--;
// Swap element to be removed with the back of the array.
Swap(index, Size);
}
#endregion
#region Public methods.
/// <summary>
/// Draw and remove an element from the set.
/// </summary>
/// <returns>Randomly picked element.</returns>
public int Draw()
{
// Local variables to be used.
int index;
int retVal;
// Various assumptions.
Debug.Assert(Size > 0);
// Get random index from remainder of set.
index = Rand.Index(Size);
// Retrieve the element at that position.
retVal = Elms[index];
// Remove that element from the set.
Remove(index);
return retVal;
}
/// <summary>
/// Reset by filling the set with integer elements enumerated
/// from zero and upwards.
/// </summary>
public void Reset()
{
// Reset index-variable.
Size = Capacity;
// Initialize array.
for (int i = 0; i < Size; i++)
{
Elms[i] = i;
}
}
/// <summary>
/// Same as Reset() only that it is being followed by a removal
/// of the designated element.
/// </summary>
/// <param name="index">Element to be removed after resetting.</param>
public void ResetExclude(int index)
{
Debug.Assert(index >= 0 && index < Capacity);
Reset();
Remove(index);
}
#endregion
}
}
|