创建魔方 (Java)

Question

我有点纠结于如何处理这个方阵编码项目。

每当我尝试输入任何值时，结果总是为真，并且方阵是魔方。例如，这会变成真的：

16 03 02 13
05 10 11 08
09 06 07 12
04 15 14 01

但是当我输入如下值时：

03 04 16 02
05 01 02 10
05 08 07 12
03 14 13 09

这应该返回 false，但它仍然返回 true，表示它是一个幻方。

要求是我需要所有的方法

"public void add(int i, int row, int col)"：在矩阵的指定位置添加一个整数。

公开

"public boolean allInRange"：判断矩阵中的所有值是否都在合适的范围内

"public boolean allUnique"：判断矩阵中的所有值是否只出现一次

"public boolean isMagic"：确定矩阵是否表示幻方。这意味着：

• 用户为某个数字 n 输入了 n^2 个数字

• 数字只在 1 和 n^2 之间，包括 1 和 n^2

• 每个数字在矩阵中只出现一次

• 每行、每列、每条对角线元素之和相等

  公共类 SquareMatrix {

  private int[][] array; 
  
  
  public SquareMatrix(int size) 
  { 
    array = new int[size][size]; 
  }
  
  
  public void add(int i, int row, int column) {array[row][column] = i;} 
  
  
  //Just checks if the #of rows & columns are between 1-n^2
  public boolean allInRange()
  {
    int n = array.length;
  
    for (int row = 0; row < n; row++)
    {
      for (int col = 0; col < array[row].length; col++)
      {
        if (array[row][col] < 1 || array[row][col] > n*n)
          return false; 
      }
    }
  
    return true;
  }
  
  public boolean allUnique()
  {
    for (int i =0; i < array.length - 1; i++)
    {
      for (int j = i + 1; j < array.length; j++)
      {
        if(array[i]==array[j])
          return false;
      }
    }
    return true;
  }
  
  
  //Supposed to call the other methods (allInRange & allUnique)
  public boolean isMagic()
  {
  
    for(int[] row : array)
    {
      for (int num : row)
      {
        if (num == 0)
          return false;
      }
    }
  
  
    boolean range = allInRange();
    if (range == true)
      return true;
    if (range == false)
      return false;
  
    boolean unique = allUnique();
    if (unique == true)
      return true;
    if (unique == false)
      return false;
  
  
  
    int sumRow;
    int sumCol;
    int sum1 = 0;
    int sum2 = 0;
  
    //Sum of Left to Right Diaganol
    for (int i = 0; i < array.length; i++)
    {
      sum1 += array[i][i];
    }
  
    //sum of right to left diaganol
    for (int j = 0; j < array.length; j++)
    {
      sum2 += array[j][array.length-1-j];
    }
  
    if (sum1 != sum2)
      return false;
  
  
    //Sum of Rows
    for (int row = 0; row < array.length; row++)
    {
      sumRow = 0;
      for (int col = 0; col < array[row].length; col++)
        sumRow += array[row][col];
  
      if (sumRow != sum1)
        return false;
    }
  
  
    //Sum of Col
    for (int i = 0; i < array.length; i++)
    {
      sumCol = 0;
      for (int j = 0; j < array.length; j++)
        sumCol = array[j][i];
  
      if (sumCol != sum1)
        return false;
  
    }
  
    return true;    
  }
  
  
  
  public String toString()
  {
    int n = array.length;
  
    String lol = "";
  
    for (int[] row : array)
    {
      for (int num : row)
      {
        String hi = String.format("%0"+(n*n+"").length()+"d",num);
  
        lol += hi + " ";
      }
      lol += "\n";
    }
    return lol;
  }
  

  }

这是我的驱动程序类

 import javax.swing.*;


public class SquareMatrixDriver { 
  
  public static void main(String[] args) { //My favorite line in history  
    
    
    JFrame bot = new JFrame(); //We can use JFrame to read the inputs 
    
    do 
    {
      //We have to make sure that it is a valid input or else I am doomed
      int size = 0;
      do 
      {
        size = Integer.parseInt(JOptionPane.showInputDialog(bot, "Enter the size of the matrix."));
        if (size < 1) 
        {
          JOptionPane.showMessageDialog(bot, "Invalid size! Enter a number greater than 0.");
        }
      } 
      while(size < 1);
      
      SquareMatrix matrix = new SquareMatrix(size);
      
      for (int i=0; i<size; i++) 
      {
        //Gets thhe User's Input
        
        String[] stringInput;
        do 
        {
          stringInput = JOptionPane.showInputDialog(bot, "Enter the row number" + (i + 1) + ", with " + size + " elements, split by commas.").split(",");
          if (stringInput.length != size) 
          { //In this code we basically enter the numbers with commas
            JOptionPane.showMessageDialog(bot, "Invalid size! " + stringInput.length + " elements entered but " + size + " required.");
          }
        } 
        while(stringInput.length != size);
        
        int[] intInput = new int[size];
        for (int o=0; o<size; o++) 
        { 
          
        }
        
        for (int o=0; o<size; o++) 
        {
          matrix.add(Integer.parseInt(stringInput[o]), i, o); //Here we would put everything into the Matrix
        }
      }
      
      
      JOptionPane.showMessageDialog(bot, "The matrix is " + (matrix.isMagic()? "very" : "not") + " correct"); //This line will output if the Matrix works or doesnt work 
      
      JOptionPane.showMessageDialog(bot, matrix); // Enters out the final output
    } while (JOptionPane.showConfirmDialog(bot, "Do you wish to exit?", "Exit", JOptionPane.YES_NO_OPTION) == 1); //Asks the User if they would like to exit the program
  }
}






      
      
     

Answer 1

目测可以发现的错误：

allUnique() 完全错误，您必须检查每个数字是否在矩阵中只出现一次，但是您正在比较完全不同的行数组，检查唯一性的最佳方法通常是使用哈希集，但是因为这里你有一个非常定义的数字范围（从 1 到 n²），所以使用任何 n² 布尔数组。扫描方阵并测试/设置数组中的对应元素，如果已经设置返回false。

public boolean allUnique() {
  int n=array.length;
  boolean[] set=new boolean[n*n];
  for (int i=0; i < n; i++) {
    for (int j=0;j < n; j++) {
      //Here assuming that you already sucessfully called allInRange, 
      //otherwise we must check bounds to avoid an index out of bounds exception
      if(set[array[i][j]-1]) {
        return false;
      }
      set[array[i][j]-1] = true;
    }
  }
  return true;
}

在方法 isMagic() 中，所有这部分都是错误和多余的

 boolean range = allInRange();
  if (range == true)
    return true;  //WRONG, this will immediately return with true, without further checks
  if (range == false)
    return false;

  boolean unique = allUnique();
  if (unique == true)
    return true;  //WRONG, same as before
  if (unique == false)
    return false;

替换为

if (!allInRange()) {
    return false;
}
if (!allUnique()) {
    return false;
}

最后在 isMagic() 中计算列的总和时，缺少加法

sumCol = array[j][i];

必须替换为

sumCol += array[j][i];