asked on

returning an array from method

I have a recursive method for geting all permutations of my array. Method is recursive because I need it like this.
I don't know how to return all posible combinations of elements in myArray. In method perRec i get all posible combinations(permutations) of indexes. I want to return this combinations and execute calculation (for elements in myArray) for each combination;

METHOD:

static public int[] perRec(int n0, int[]a)
       {
int zaporedje_indeksov[]=new int [a.length];
       if(n0==0){
              for ( int j=0; j<a.length ;j++) {
              zaporedje_indeksov[j] = a[j];
                         }
              return zaporedje_indeksov;
                         }
       else
             {
       for(int i=0, temp; i < n0; i++) {
       temp = a[i]; a[i] = a[n0-1]; a[n0-1] = temp;
       perRec(n0-1, a);
       temp = a[i]; a[i] = a[n0-1]; a[n0-1] = temp;
                                                }
             }
return zaporedje_indeksov;}

CALLING OF METHOD:

for (int i=0; i<myArray.length;i++)
tabelaIndeksov[i]=i;      // initialization

     Podatki.perRec(dolzina, tabelaIndeksov);
      // here I must get all combinations of values in MyArray and for each combination execute calculation

StillUnAware

If You can, do Your subsequent calculations inside perRec function

static public int[] perRec(int n0, int[]a)
{
int zaporedje_indeksov[]=new int [a.length];
if(n0==0){
for ( int j=0; j<a.length ;j++) {
zaporedje_indeksov[j] = a[j];
}
return zaporedje_indeksov; <-- instead of this return statement perform needed calculations
}
else
{...

or use global array to store each zaporedje_indeksov array instead of returning it,
the array size should be [factorial(a.length)][zaporedje_indeksov.length], also You'll have to write function 'factorial'

tomaz108

ASKER

How can I use global array, myArray is in another class. I'm begginer in Java so I need basic instructions. Thank you.

StillUnAware

You can have this big array in your class alog with myArray, and use anywhere you want.

bhaskar20001

Try like this..I didn't tested it..

static int[] myNewArray = null;
static public void perRecNew(int n0, int[]a)
{
if(myNewArray == null){
myNewArray = new int[factorial(a.length)][a.length];
}
int zaporedje_indeksov[]=new int [a.length];
myNewArray[n0]=perRec(n0,a,zaporedje_indeksov);
}

static public int[] perRec(int n0, int[] a,int[] zaporedje_indeksov)
{
if(n0==0){
for ( int j=0; j<a.length ;j++) {
zaporedje_indeksov[j] = a[j];
}
return zaporedje_indeksov;
}
else
{
for(int i=0, temp; i < n0; i++) {
temp = a[i]; a[i] = a[n0-1]; a[n0-1] = temp;
perRec(n0-1, a);
temp = a[i]; a[i] = a[n0-1]; a[n0-1] = temp;
}
}
return zaporedje_indeksov;
}

public int[] getMyPerCom()
{
return myNewArray;
}

----------------------------------
CALLING OF METHOD:

for (int i=0; i<myArray.length;i++)
{
tabelaIndeksov[i]=i; // initialization
Podatki.perRec(dolzina, tabelaIndeksov);
}
int[] perCom = Podatki.getMyPerCom();

tomaz108

ASKER

I'm trying to do like this:

static public int[][] perRec(int n0, int[]a, int fak)
{
int x = 0;
int zaporedje_indeksov[][]=new int [a.length][fak];

if(n0==0){
for ( int j=0; j<a.length ;j++) {
zaporedje_indeksov[j][x] = a[j];
}
x++;
}
else
{
for(int i=0, temp; i < n0; i++) {
temp = a[i]; a[i] = a[n0-1]; a[n0-1] = temp;
perRec(n0-1, a, fak);
temp = a[i]; a[i] = a[n0-1]; a[n0-1] = temp;
}
}
return zaporedje_indeksov;
}

     int fak = Podatki.fakulteta(dolzina);      // fakulteta returns faculty of dolzina

     for (int i=0; i<tabela.length;i++)      // initialization
tabelaIndeksov[i]=i;

      for (int j=0; j<fak;j++)       // test
for (int i=0; i<tabela.length;i++)
System.out.println (Podatki.perRec(dolzina, tabelaIndeksov, fak)[i][j]);

But I get only zero: 0 0 0 0 0 0...

tomaz108

ASKER

can somebody help me?

ASKER CERTIFIED SOLUTION

bhaskar20001

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