Pascal.java

Below is the syntax highlighted version of Pascal.java from §1.4 Arrays.

/******************************************************************************
 *  Compilation:  javac Pascal.java
 *  Execution:    java Pascal n
 *
 *  Computes and prints out Pascal's triangle or order n.
 *  Illustrated ragged arrays in Java.
 *
 *  % java Pascal 7
 *  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
 *
 ******************************************************************************/

public class Pascal {
    public static void main(String[] args) {
        int n = Integer.parseInt(args[0]);
        int[][] pascal  = new int[n+1][];

        // initialize first row
        pascal[1] = new int[1+2];
        pascal[1][1] = 1;

        // fill in Pascal's triangle
        for (int i = 2; i <= n; 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];
        }

        // print results
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j < pascal[i].length - 1; j++) {
                System.out.print(pascal[i][j] + " ");
            }
            System.out.println();
        }
    }
}