#include <stdio.h>
#include "towers.h"

/* ---------------------------------------------------------------------- */
/* Solve the problem for npieces disks */

solve_tower(Dllist *towers, int from, int to, int npieces)
{
  int other;
  int i;

  /* Find the identity of the other tower */

  for (i = 0; i < 3; i++) {
    if (from != i && to != i) other = i;
  }

  /* Move the top n-1 pieces to the other tower */

  if (npieces > 1) {
    solve_tower(towers, from, other, npieces-1);
  }

  /* Move the remaining piece to the destination */

  make_move(towers, from, to);

  /* Move the top n-1 pieces onto the destination */

  if (npieces > 1) {
    solve_tower(towers, other, to, npieces-1);
  }
}



/* ---------------------------------------------------------------------- */
/* Main -- allocate, print, solve, print */

main(int argc, char **argv)
{
  Dllist *towers;
  int npieces;

  if (argc != 2) {
    fprintf(stderr, "usage: tower_solution size\n");
    exit(1);
  }

  npieces = atoi(argv[1]);
  if (npieces <= 0) exit(1);

  towers = new_towers(npieces);
  print_towers(towers);
  solve_tower(towers, 0, 1, npieces);
  print_towers(towers);
}