main.c

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <time.h>

#define NUMBER 1000000

int main(void) {
  int *result;
  result = (int *) malloc(NUMBER*sizeof(int));

  srand(time(0));
  int current = 0;
  const int step = INT_MAX / NUMBER;
  int limit = step;
  int index = 0;

  //Generate unique set:
  for (; index < NUMBER; ++index) {
    current += 1 + rand() % (limit-current);
    limit += step;
    result[index] = current;
  }

  //Shuffle the set:
  for (index = 0; index < NUMBER; ++index) {
    current = result[index];
    limit = rand() % NUMBER;
    result[index] = result[limit];
    result[limit] = current;
  }  

  //Print out the set:
  int separator = 0;
  
  for (index = 0; index < NUMBER; ++index) {
    ++separator;
    if (separator == 6) {
      printf("%11d\n", result[index]);
      separator = 0;
    } else {
      printf("%11d ", result[index]);
    }
  }

  free(result);

  return 0;
}