// Narayana's Algorithm
// Generates the next permutation in the series, in place
void GeneratePermutation(LPBYTE Elements, BYTE setSizeBytes)
{
 // Find the largest index k such that a[k] < a[k + 1].
 short k, l, largestIndex = -1;
 for(k = (setSize - 2); k >= 0; k--)
 {
     if(Elements[k] < Elements[k+1])
     {
        if(k > largestIndex)largestIndex = k; 
     }
 }

 // If no such index exists, the permutation is the last permutation.
 if(largestIndex == -1)return;

 // Find the largest index l such that a[k] < a[l].
 // Since k + 1 is such an index, l is well defined and satisfies k < l.
 k = largestIndex;
 largestIndex = -1;
 for(l = (setSize - 1); l >= 1; l--)
 {
     if(Elements[k] < Elements[l])
     {
        if(l > largestIndex)largestIndex = l; 
     }
 }

 // Swap a[k] with a[l].
 l = largestIndex;
 BYTE tmp = Elements[k];
 Elements[k] = Elements[l];
 Elements[l] = tmp;

 // Reverse the sequence from a[k + 1] up to and including the final element a[n].
 ++k; l = setSizeBytes - 1;
 while(l > k)
 {
       tmp = Elements[k];
       Elements[k] = Elements[l];
       Elements[l] = tmp;
       ++k; --l;
 }
}