/*
 * This code is from "Algorithms in C, Third Edition,"
 * by Robert Sedgewick, Addison Wesley Longman, 1998.
 */
void PQsort(Item a[], int l, int r)
  { int k;
    PQinit();
    for (k = l; k <= r; k++) PQinsert(a[k]);
    for (k = r; k >= l; k--) a[k] = PQdelmax();
  }