| public Choose ( int n ) : int | ||
| n | int | The exclusive upper bound of the random number to be generated. n must be /// greater than or equal to zero. |
| Résultat | int | |
public int Choose(int n)
{
if (n < 0)
{
throw new ArgumentOutOfRangeException("n", "n must be non-negative.");
}
if (n <= 1)
{
return 0;
}
uint result;
uint msb = this.GetMostSignificantBit((uint)n);
uint mask = msb - 1;
double probabilityOfMsbBeingOne = ((double)n - msb) / n;
if (this.ChooseDouble() < probabilityOfMsbBeingOne)
{
result = msb + (uint)this.Choose(n - (int)msb);
}
else
{
byte[] randomData = new byte[sizeof(uint)];
Chooser.randomNumberGenerator.GetBytes(randomData);
uint randomInt = BitConverter.ToUInt32(randomData, 0);
result = randomInt & mask;
}
return (int)result;
}
/// <summary>
/// Generates a random member accepted by fa.
/// Assumes that fa has no dead states, or else termination is not guaranteed.
/// </summary>
public string GenerateMember(Automaton <HashSet <Tuple <char, char> > > fa)
{
if (fa.IsEmpty)
{
throw new AutomataException(AutomataExceptionKind.AutomatonMustBeNonempty);
}
var sb = new System.Text.StringBuilder();
int state = fa.InitialState;
while (!fa.IsFinalState(state) || (fa.OutDegree(state) > 0 && chooser.ChooseTrueOrFalse()))
{
var move = fa.GetNthMoveFrom(state, chooser.Choose(fa.GetMovesCountFrom(state)));
if (!move.IsEpsilon)
{
Tuple <char, char> someRange = new Tuple <char, char>('\0', '\0');
foreach (var range in move.Label)
{
someRange = range;
break;
}
int offset = chooser.Choose(Math.Max(1, (int)someRange.Item2 - (int)someRange.Item1));
char someChar = (char)((int)someRange.Item1 + offset);
sb.Append(someChar);
}
state = move.TargetState;
}
return(sb.ToString());
}