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  1.     using System;
  2.     using System.Linq;
  3.     using System.Collections.Generic;
  4.  
  5.     public class Test
  6.     {
  7.  
  8.         static Random random = new Random();
  9.  
  10.         public static List<int> GenerateRandom(int count, int min, int max)
  11.         {
  12.  
  13.             //  initialize set S to empty
  14.             //  for J := N-M + 1 to N do
  15.             //    T := RandInt(1, J)
  16.             //    if T is not in S then
  17.             //      insert T in S
  18.             //    else
  19.             //      insert J in S
  20.             //
  21.             // adapted for C# which does not have an inclusive Next(..)
  22.             // and to make it from configurable range not just 1.
  23.  
  24.             if (max <= min || count < 0 || 
  25.                     // max - min > 0 required to avoid overflow
  26.                     (count > max - min && max - min > 0))
  27.             {
  28.                 // need to use 64-bit to support big ranges (negative min, positive max)
  29.                 throw new ArgumentOutOfRangeException("Range " + min + " to " + max + 
  30.                         " (" + ((Int64)max - (Int64)min) + " values), or count " + count + " is illegal");
  31.             }
  32.  
  33.             // generate count random values.
  34.             HashSet<int> candidates = new HashSet<int>();
  35.  
  36.             // start count values before max, and end at max
  37.             for (int top = max - count; top < max; top++)
  38.             {
  39.                 // May strike a duplicate.
  40.                 // Need to add +1 to make inclusive generator
  41.                 // +1 is safe even for MaxVal max value because top < max
  42.                 if (!candidates.Add(random.Next(min, top + 1))) {
  43.                     // collision, add inclusive max.
  44.                     // which could not possibly have been added before.
  45.                     candidates.Add(top);
  46.                 }
  47.             }
  48.  
  49.             // load them in to a list, to sort
  50.             List<int> result = candidates.ToList();
  51.  
  52.             // shuffle the results because HashSet has messed
  53.             // with the order, and the algorithm does not produce
  54.             // random-ordered results (e.g. max-1 will never be the first value)
  55.             for (int i = result.Count - 1; i > 0; i--)
  56.             {  
  57.                 int k = random.Next(i + 1);  
  58.                 int tmp = result[k];  
  59.                 result[k] = result[i];  
  60.                 result[i] = tmp;  
  61.             }  
  62.             return result;
  63.         }
  64.  
  65.         public static List<int> GenerateRandom(int count)
  66.         {
  67.             return GenerateRandom(count, 0, Int32.MaxValue);
  68.         }
  69.  
  70.  
  71.         // TEST CODE BELOW HERE
  72.  
  73.         class Counter {
  74.             public int Count { get; set; }
  75.         }
  76.  
  77.         public static string IntsToString(List<int> data) {
  78.             return string.Join(", ", data.Select(x => x.ToString()).ToArray());
  79.         }
  80.  
  81.         public static void Main()
  82.         {
  83.             try {
  84.                 List<int> vals = GenerateRandom(10);
  85.                 Console.WriteLine("Result: " + vals.Count);
  86.                 vals.ForEach(Console.WriteLine);
  87.  
  88.                 Console.WriteLine();
  89.  
  90.                 GenerateRandom(10, Int32.MinValue, Int32.MaxValue).ForEach(Console.WriteLine);
  91.  
  92.                 Console.WriteLine();
  93.  
  94.                 SortedDictionary<string,Counter> counts = new SortedDictionary<string,Counter>();
  95.                 for (var i = 0; i < 24000; i++)
  96.                 {
  97.                     List<int>varray = GenerateRandom(3, 0, 4);
  98.                     //varray.Sort();
  99.                     string v = IntsToString(varray);
  100.                     if (!counts.ContainsKey(v))
  101.                     {
  102.                         counts.Add(v, new Counter());
  103.                     }
  104.                     //Console.WriteLine("Processing " + v + " with counts " + counts[v].Count);
  105.                     counts[v].Count = counts[v].Count + 1;
  106.  
  107.                 }
  108.  
  109.                 foreach (string key in counts.Keys)
  110.                 {
  111.                     Console.WriteLine("{0} -> {1}", key, counts[key].Count);
  112.                 }
  113.             }
  114.             catch (Exception e)
  115.             {
  116.                 Console.WriteLine("{0} Exception caught.", e);
  117.             }
  118.         }
  119.     }
  120.  
Success #stdin #stdout 0.51s 34520KB
comments (?)
stdin 
Standard input is empty
stdout 
Result: 10
1170697438
120105513
855090899
763869798
775127055
1193185824
778291465
565942465
1570240628
3835490

1385019287
-404232386
556571568
-1518374403
-777106293
1231209584
-897704110
-1961167793
2082881277
1931032930

0, 1, 2 -> 1016
0, 1, 3 -> 1069
0, 2, 1 -> 1005
0, 2, 3 -> 1001
0, 3, 1 -> 962
0, 3, 2 -> 956
1, 0, 2 -> 1038
1, 0, 3 -> 936
1, 2, 0 -> 1064
1, 2, 3 -> 985
1, 3, 0 -> 1024
1, 3, 2 -> 949
2, 0, 1 -> 1048
2, 0, 3 -> 1004
2, 1, 0 -> 982
2, 1, 3 -> 991
2, 3, 0 -> 965
2, 3, 1 -> 1043
3, 0, 1 -> 1042
3, 0, 2 -> 983
3, 1, 0 -> 944
3, 1, 2 -> 949
3, 2, 0 -> 1000
3, 2, 1 -> 1044
https://ideone.com/ffubfh
language:
C# (gmcs 5.20.1)
created:
11 years ago
visibility:
public

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