2d array mathematical sequence (Java)

So I have to print out an array which:

  • The first cell defines the dimension of the square array. So, I have the input Scanner.
  • On the first row of the array, every cell has to be the triple of the previous one minus one.
  • For every next row, every cell has to have the double of the same column of the previous line, plus the number of the column.
  • For example: if the input of the dimensions is 4, like showArrray(creerArray(4));, then it should print something like:
    4 11 32 95
    
    8 23 66 193
    
    16 47 134 389

    32 95 270 781

I already coded the part for the input dimension, but I am stuck at trying to figure out how to code this sequence:

public static void showArray() {
    
}
 
public static void  createArray() {
    int square= 0;
    int[][] int2D = new int[square][square];

    java.util.Scanner input = new Scanner(System.in);
    square= input.nextInt();
    System.out.println("Enter the dimension of the array:" + square);
    int counter=0;
    for(int i=0; i<square; i++) {
        for(int j=0; j<square; j++){
            int2D[i][j]=counter;
            counter++;
        }
        input.close();
        
    }
    ****i have to start coding the sequence here
        
}

Answer

It’s all a matter of where you place your calculations within the for loops to generate the 2D Array, for example:

// Get Array size from User...
Scanner userInput = new Scanner(System.in);

int aryLength = 0; // To hold the square 2D Array Rows and Columns length.
while (aryLength == 0) {
    System.out.print("Enter 2D Array square size: --> ");
    String len = userInput.nextLine();
    /* Is the supplied value valid...
       The Regular Expression passed to the String#matches() method
       will return boolean true is the variable len only contains
       a string representation of a signed or unsigned integer 
       value.        */ 
    if (len.matches("-?\d+")) {
        // Yes it is:  
        aryLength = Integer.valueOf(len);
    }
    else {
        System.err.println("Invalid numerical value (" + len + ") supplied!");
        System.err.println(); 
    }
}

// Declare and initialize the 2D Array
int[][] array = new int[aryLength][aryLength];

int startVal = aryLength; // Used to calculate the first cell of every array Row
// Iterate array Rows...
for (int i = 0; i < array.length; i++) {
    // Iterate Columns of each array row...
    int cellVal = startVal; // Used for the cell values for all columns in each row
    for (int j = 0; j < aryLength; j++) {
        array[i][j] = cellVal;
        cellVal = ((array[i][j] * 3) - 1); // calculate cell value
    }
    startVal = startVal * 2; // Calculate first cell value for very row.
}

// Display the 2D Array
System.out.println();
for (int i = 0; i < array.length; i++) {
    System.out.println(Arrays.toString(array[i]).replaceAll("[\[\]]", ""));
}

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