从列表中选择一个随机变量。 如果不是所选的，则选择另一个。

Question

I have this Guess the number game. The user thinks of a number and the computer will guess it. I have this code but the thing is, every attempt that computer makes there's a chance that the random number will repeat. I would like to know how to create a random list, the computer will pick a number from the list, if it's not correct I would like to have that number deleted so it will not be picked up again. I am new in this field so I would really appreciate any help.

private void btnStartTheGame_Click(object sender, EventArgs e)
{
    int guessTheNumber = Convert.ToInt32(txtNumberGuess.Text);
    DialogResult dialogResult;
    do
    {
        Random newNumberGenerator = new Random();
        number = newNumberGenerator.Next(0, 10);
        dialogResult = MessageBox.Show("Is number" + number.ToString() + " you are thinking about?", "Answer the question!", MessageBoxButtons.YesNo);
    }while (dialogResult == DialogResult.No);

    MessageBox.Show("Congratulation! You guessed the number!!");       
}

Answer 1

List<int> randomNumbers = Enumerable.Range(0,10).ToList();
DialogResult dialogResult;
Random newNumberGenerator = new Random();
do
{
    int index = newNumberGenerator.Next(0, randomNumbers.Count);
    dialogResult = MessageBox.Show("Is number" + randomNumbers[index] + " you are thinking about?", "Answer the question!", MessageBoxButtons.YesNo);
    if(dialogResult==DialogResult.No)
    {
        randomNumbers.RemoveAt(index);
    }
}
while (dialogResult == DialogResult.No);

Answer 2

Here is a short but complete program which does as you require (I have used a console application rather than forms):

private static void Main(string[] args)
{
    string dialogResult = "";
    bool[] alreadyGuessed = new bool[10];
    int guesses = 0;

    Random newNumberGenerator = new Random();
    do
    {
        int number = newNumberGenerator.Next(0, 10);
        if (!alreadyGuessed[number])
        {
            guesses++;
            alreadyGuessed[number] = true;
            Console.WriteLine("Are you thinking of the number " + number.ToString() + "?")
            dialogResult = Console.ReadLine();
        }
    }
    while (dialogResult.ToUpper() != "Y" && guesses < 10);

    if (dialogResult.ToUpper() == "Y")
    {
        Console.WriteLine("I guessed the number!");
    }
    else
    {
        Console.WriteLine("No numbers left!");
    }
    Console.ReadLine();
}

The logic in your original program seemed somewhat backwards; it wasn't clear whether it was the user or the computer doing the guessing. This program assumes that you are thinking of a number between 0 and 9 (inclusive) and leaving the computer to try to guess it, but you can obviously adapt it to your needs. I have also omitted any validation logic.

EDIT : As Tarec correctly points out, this doesn't extend to very large number sets. To do that you'd need a proper shuffling algorithm like this:

public static void Shuffle(int[] array)
{
    var random = new Random();
    for (int i = array.Length; i > 1; i--)
    {
        int j = random.Next(i);
        int temp = array[j];
        array[j] = array[i - 1];
        array[i - 1] = temp;
    }
}

Then you could change your program to this:

private static void Main(string[] args)
{
    string dialogResult = "";
    int size = 10;

    int[] array = Enumerable.Range(0, size).ToArray();
    Shuffle(array);

    for (int i = 0; i < size; i++)
    {
        int number = array[i];
        Console.WriteLine("Are you thinking of the number " + number.ToString() + "?");
        dialogResult = Console.ReadLine();
        if (dialogResult.ToUpper() == "Y")
        {
            break;
        }
    }

    if (dialogResult.ToUpper() == "Y")
    {
        Console.WriteLine("I guessed the number!");
    }
    else
    {
        Console.WriteLine("No numbers left!");
    }
    Console.ReadLine();
}

Now you can change 'size' to whatever you like and the program will work correctly. This is probably overkill for the original poster's needs, though.

Answer 3

I modified your code by adding an array of number to be chosen. Then I random only the index of the array. If the number if not correct, the number is removed from the array and redo again.

int guessTheNumber = Convert.ToInt32(txtNumberGuess.Text);
DialogResult dialogResult;
ArrayList numberList = new ArrayList();
for(int i=1; i<10; i++)
   numberList.Add(i);
int length = index.Count;
do
{
   Random newNumberGenerator = new Random();
   index = newNumberGenerator.Next(length);
   dialogResult = MessageBox.Show("Is number" + numberList[index].ToString() + " you are thinking about?", "Answer the question!", MessageBoxButtons.YesNo);
   if( dialogResult == DialogResult.No) 
   {
      numberList.RemoveAt(index);
      length = length - 1;
      if(length == 0)
      {
          MessageBox.Show("No number left!!");  
          return;
      }
   }
}while (dialogResult == DialogResult.No);
MessageBox.Show("Congratulation! You guessed the number!!");