Partition of a natural number

Question

hello
i want to find out the partition of natural numbers.
e.g. the partion of 4
p(4) = 5 = {(4), (1,3), (2,2), (1,1,2), (1,1,1,1)}
can someone help me with a short code example?
any hints are appreciated as i am new to java...
greets

Answer 1

okay so far i have got the following code: the problem is that for p(n) with n> 10 the results are getting wrong. Any hints on this???
import java.lang.*;
public class Partition {
    static int size = 10;
    static int counter = 0;
    static int current[] = new int[size];
    static int parts = 0;
    static void partition(int n,int k) {
        //ende der rekursiven Aufrufe und ausgabe
        if (n==0) {
            print(current);
            //erzeugt temp feld
            int[] aux = new int[counter];
            System.arraycopy(current,0,aux,0,counter);
            current = new int[size];
            System.arraycopy(aux,0,current,0,counter-1);
        else {
            for (int i=k; i>0 && n>0; i--) {
                if(n!=1) {
                    current[counter++]=i;
                    partition(n-i,i);
                else {
                    current[counter++]=1;
                    print(current);
                    counter--;
                    break;
                counter--;
    static void print(int input[]) {
        for(int i=0; i<10; i++) {
            if (input[i] != 0) //nullen weglassen
                System.out.print(input[i]+":");
        System.out.println();
        parts++;
    public static void main(String[] args) {
        if (args.length<1) {
            System.out.println("Usage:\njava Partition IntWert");
            System.exit(1);
        if (Integer.parseInt(args[0]) > size) {
            System.out.println("Bitte Wert kleiner "+size+" eingeben!");
            System.exit(1);
        else {
            int n=Integer.parseInt(args[0]);
            partition(n,n);
        System.out.println("\np("+args[0]+") = "+parts);
}