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Pascal’s triangle 2d array – formatting printed output

I have a small assignment where I have to use a 2d array to produce Pascal’s triangle. Here is my code, and it works. There is an extra credit opportunity if I display the triangle like so:

Pascal's triangle

However, my spacing is not formatted like that. it simply displays the numbers all lined up on the left. its hard to describe but if you run it you will see what I mean.

Here is my code:

public class Pascal {
    public static final int ROW = 16;
    public static void main(String[] args) {
        int[][] pascal = new int[ROW + 1][];
        pascal[1] = new int[1 + 2];
        pascal[1][1] = 1;
        for (int i = 2; i <= ROW; i++) {
            pascal[i] = new int[i + 2];
            for (int j = 1; j < pascal[i].length - 1; j++) {
                pascal[i][j] = pascal[i - 1][j - 1] + pascal[i - 1][j];
            }
        }
        for (int i = 1; i <= ROW; i++) {
            for (int j = 1; j < pascal[i].length - 1; j++) {
                System.out.print(pascal[i][j] + " ");
            }
            System.out.println();
        }
    }
}

If someone could help me figure out how to add the correct spacing to my program to produce the output desired in the picture, that would be great. I know I need to put a System.out.print(" ") somewhere. I just dont know where.

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Answer

Here I had modified your code, it prints wonderfully for ROW size till 13, because of the limitation of my console window:

import java.util.*;

public class Pascal {
    public static final int ROW = 12;
    private static int max = 0;

    public static void main(String[] args) {
        int[][] pascal = new int[ROW + 1][];
        pascal[1] = new int[1 + 2];
        pascal[1][1] = 1;
        for (int i = 2; i <= ROW; i++) {
            pascal[i] = new int[i + 2];
            for (int j = 1; j < pascal[i].length - 1; j++) {
                pascal[i][j] = pascal[i - 1][j - 1] + pascal[i - 1][j];
                String str = Integer.toString(pascal[i][j]);
                int len = str.length();
                if (len > max)
                    max = len;
            }
        }

        for (int i = 1; i <= ROW; i++) {
            for (int k = ROW; k > i; k--)
                System.out.format("%-" + max + "s", " ");
            for (int j = 1; j < pascal[i].length - 1; j++)
                System.out.format("%-" + (max + max) + "s", pascal[i][j]);
            System.out.println();
        }
    }
}

Output:

                                 1     
                              1     1     
                           1     2     1     
                        1     3     3     1     
                     1     4     6     4     1     
                  1     5     10    10    5     1     
               1     6     15    20    15    6     1     
            1     7     21    35    35    21    7     1     
         1     8     28    56    70    56    28    8     1     
      1     9     36    84    126   126   84    36    9     1     
   1     10    45    120   210   252   210   120   45    10    1     
1     11    55    165   330   462   462   330   165   55    11    1     
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