#include <stdlib.h>

static void swap(int& i, int& j) {
  int temp = i;
  i = j;
  j = temp;
}

static int randSlot(int i) { // return a random int from 0 to i inclusive
  double r = double(rand())/RAND_MAX;

  int retVal = int(r*(i+1));
  if(retVal > i) {
    return 0;
  }
  return retVal;
}

int* permList(int sz) {
  int *retVal = new int[sz];

  int i;
  for(i = 0; i < sz; i++) {  // put all the numbers in
    retVal[i] = i;
  }

  for(i--; i > 0; i--) {  // choose the value of each slot in desc. order
    swap(retVal[i], retVal[randSlot(i)]);
  }

  return retVal;
}