algorithm psudocode trouble coding it to java

[Jeff Yan]

hey all, im struggling abit with some psudocode that i have to convert to java. basically im writing a quicksort algorithm which i have been supplied the psudocode for. but im having trouble analysing the psudocode on what part of it.

the bit i am stuck on is it says:

swap(A,pL,pR)

with A being the array of integers i have, and pL and pR being integers of some sort. here is the full psudocode; it is to partition the array before sorting:

   Algorithm: partition
Inputs: A: Array of integers; left, right: Integer
Returns: pL: Integer
Variables: pL, pR, v: Integer;
Begin
        v := A[right]
        pL := left; pR := right
        while (pL < pR) do
             while (A[pl] < v) do pL := pL + 1 od
             while (A[pR]>=v and pR > left) do pR := pR - 1 od
             if (pL < pR) then swap(A,pL,pR) fi
         od
         swap ( A, pL, right);
         return pL;
End  

the code i have got for it so far is:

 private int partition(int left, int right)
        {
            int v = data[right];
            int pL = left;
            int pR = right;
            while (pL < pR)
            {
                while ( data[pL] < v)
                {
                    pL ++;
                }while ( data[pR] >= v &&pR > left)
                {
                    pR --;
                }
                if (pL < pR)
                {
                    int temp;
                   // swap(a,pL,pR)
                }
            }
           // swap(A,pL,right)
            return pL;
        }    

does anybody have any idea?

[Campbell Ritchie]

It means you write a swap() method and call it from that if block.

[Jeff Yan]

right, but what exactly am i swapping?! :s

[Campbell Ritchie]

Not sure. Try the elements of the array pointed to by the numbers "left" and "right"

Or Google for quicksort and you are bound to find the algorithm explained. I can't remember the details of quicksort. If you do Google you will find (inter alia) this, this and this. You will probably understand the first two of those links

[Jeff Yan]

ok cheers mate

[Campbell Ritchie]

You're welcome, and good luck with it