创建幻方 (Java)

Question

我有点不知道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，方阵是一个幻方。例如，结果会是这样：

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 return 错误，但它仍然 return 正确地说它是一个幻方。

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。

public

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"：判断矩阵是否说明幻方。这意味着：

用户输入了 n^2 个号码，对应号码 n
数字只能在1到n^2之间，包括在内
每个数字在矩阵中只出现一次

每行、每列、两条对角线的元素之和相等

public class 方阵 {

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driverclass

 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

我可以通过目测发现的错误：

allUnique() 是完全错误的，你必须检查每个数字是否只在矩阵中出现一次，但是你正在比较完全不同的行数组，检查唯一性的最好方法通常是使用hashset，但是因为这里你有一个非常定义的数字范围（从 1 到 n²），然后使用 n² 布尔值的任何数组。扫描方阵和test/set数组中对应的元素，如果已经设置returnfalse.

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 isMagic() 方法中，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;

直接替换为

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];

创建幻方 (Java)

Creating a magic square (Java)

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