BinomialTheorem.java

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

/*************************************************************************
 *  Compilation:  javac BinomialTheorem.java
 *  Execution:    java BinomialTheorem N
 *
 *  Prints out (x+y)^N for positive integer N using the Binomial Theorem
 *  and Pascal's triangle.
 *
 *  % java BinomialTheorem 5
 *  1 5 10 10 5 1
 *
 *  % java BinomialTheorem 10
 *  1 10 45 120 210 252 210 120 45 10 1
 *
 *************************************************************************/

public class BinomialTheorem {
    public static void main(String[] args) {
        int N = Integer.parseInt(args[0]);
        int[] a    = new int[N+1];
        int[] aold = new int[N+1];

        // initialize a[0] = 1, a[i] = 0 for i > 0
        a[0] = 1;

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

            // copy current values
            for (int j = 0; j <= N; j++) {
                aold[j] = a[j];
            }

            // update new values
            for (int j = 1; j <= N; j++) {
                a[j] = aold[j] + aold[j-1];
            }
        }

        // print results
        for (int i = 0; i <= N; i++) {
            System.out.print(a[i] + " ");
        }
        System.out.println();
    }

}