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Suppose, I take a one-dimensional array of integer

A = {1,2,3,4,5,6,7,8, 9, 10, 11, 12}

Now, I want to to rearrange the integers in A in a two dimensional array with p rows and q columns in diagonal fashion. Where, p=3 and
q=4.

Output will be like this:

1 2 4 7

3 5 8 10

6 9 11 12

You can do it like this,

public class Main {



    public static void main(String args) {

        int array = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12};

        int diagonalArray = createDiagonalArray(array, 3, 4);

        print2DArray(diagonalArray);

    }



    private static int createDiagonalArray(int array, int p, int q) {



        int input = new int[p][q];

        for (int j = 0; j < p; j++) {

            for (int i = 0; i < q; i++) {

                input[j][i] = array[j * q + i];

            }

        }



        final int numRows = input.length;

        final int numColumns = input[0].length;

        int result = new int[numRows][numColumns];



        int rowIndex = 0;

        int columnIndex = 0;

        int currentRow = 0;

        int currentColumn = 0;

        for (int i = 0; i < numRows; i++) {

            for (int j = 0; j < numColumns; j++) {

                result[currentRow][currentColumn] = input[i][j];

                if (currentRow == numRows - 1) {

                    if (numRows < numColumns && columnIndex < numColumns - 1) {

                        currentRow = 0;

                        currentColumn = ++columnIndex;

                    } else {

                        currentRow = ++rowIndex;

                        currentColumn = numColumns - 1;

                    }

                } else if (currentColumn == 0) {

                    if (columnIndex < numColumns - 1) {

                        currentRow = rowIndex;

                        currentColumn = ++columnIndex;

                    } else {

                        currentColumn = columnIndex;

                        currentRow = ++rowIndex;

                    }

                } else {

                    currentRow++;

                    currentColumn--;

                }



            }

        }

        return result;

    }



    private static void print2DArray(int diagonalArray) {

        for (int j = 0; j < 3; j++) {

            for (int i = 0; i < 4; i++) {

                System.out.print(diagonalArray[j][i] + " ");

            }

            System.out.println();

        }

    }

}

The two dimensional part was taken from here

You can try the following approach:

1) Initialize a 2d array of the specified dimension, i.e p by q

2) For each cell in the first row, fill its anti-diagonal ( like from north-east to south-west direction) with the next available elements in your 1d array.

3) After the first row is processed, similarly do step 2 for each remaining cell in the last column of the 2d array.

Finally, your 2d array will hold the answer you want (i.e numbers filled in an anti-diagonal fashion)

To have this result you could do this:

int z = 0;

for(int i = 0; i < 3; i++){

    for (int j = 0; j < 4; j++){

       System.out.print(A[z]);

       z++;

    }

   System.out.println();

}

This uses nested for loops to loop through the i and j, equivalent to the p and q rows and columns. The inner loop includes a z counter, which is the index in the original array. Be sure to include a definition of A in your code.