java - java中如何删除二维数组中的重复项？

Question

我正在尝试通过 2D 数组生成数独板:board[5][5]。数独板应该只包含独特的元音。然而，我只是让独特的元音连续出现。对于列，它们似乎仍然有重复项。我该如何使用迄今为止的代码生成一个没有重复项的列？

这是我用于连续生成唯一字母的代码:

String [] vowels = {"A","E","I","O","U"};
String [][] board = new String [vowels.length][5];

public Actions(){
    int rows = 5;
    for(int row = 0;row<rows;row++){
        ArrayList<String> tempVowels = new ArrayList<String>(Arrays.asList(vowels));
        int numVowPerLine = (int)Math.floor(Math.random()*4);
        for(int j = 0;j<numVowPerLine;j++){
            do{
                int pos = (int)Math.floor(Math.random()*5);
                if(board[row][pos] == null){
                    int temp = (int)Math.floor(Math.random()*tempVowels.size());
                    board[row][pos] = tempVowels.get(temp);
                    tempVowels.remove(temp);
                    break;
                }   
            }while(true);
        }

    }

致谢:L7ColWinters

Answer 1

这与一个众所周知的问题有关，称为 Rooks Problem .

我可以建议一个更简单的循环吗？

编辑:阅读评论后，我发现问题需要应用于每个元音。在我看来，这更具可读性:

java.util.Random random = new Random();

boolean[] r_occupied;
boolean[] c_occupied;

for (i = 0; i < vowels.length; i++)
  {
    // Clear the 'occupied' information
    r_occupied = new boolean[5];
    c_occupied = new boolean[5];

    // we will put vowel[i] 'count' times into the 'board'
    count = random.nextInt(5);

    for (j = 0; j < count; j++)
      {
        // generate a random row
        row = random.nextInt(5);

        // if it is already occupied, select the next one
        while (r_occupied[row])
          row = (row + 1) % 5;

        // generate a random column
        col = random.nextInt(5);

        // if it is already occupied, select the next one
        while (c_occupied[col])
          col = (col + 1) % 5;

        /* put the vowel at board[row][col] */
        r_occupied[row] = true;
        c_occupied[col] = true;
        board[row][col] = vowel[i];
      }
  }

注意:它会覆盖一些元音，但这应该没问题。