Beispiel #1
0
  /**
   * Somewhat multi-threaded depth-first search. Performs a DFS of the subtrees from the current
   * node in parallel.
   *
   * @param s The tile sequence
   * @param b The board to search
   * @param pool The thread pool in which to submit jobs to.
   * @return The board with the highest evaluation or null if no board can continue.
   */
  private Board solve_pdfs(Board b, ExecutorService pool) {
    List<Future<Board>> rets = new ArrayList<>(BOARD_WIDTH);
    Board best = null;
    int best_score = -1;

    for (Direction d : directions) {
      Board n = new Board(b);
      if (n.move(tileSequence, d)) {
        rets.add(pool.submit(new ParallelDFS(n)));
      }
    }

    for (Future<Board> ret : rets) {
      try {
        Board c = ret.get();
        if (c != null) {
          int score = evaluate(c);
          if (score > best_score) {
            best = c;
            best_score = score;
          }
        }
      } catch (InterruptedException | ExecutionException e) {
        System.err.println("Error: " + e.getMessage());
      }
    }

    return best;
  }
Beispiel #2
0
  private Board solve_dfs(Board b, int depthLimit, int depth) {
    if (depth >= depthLimit) { // Cutoff test
      return b;
    }

    Board best = null;
    int best_score = -1;

    for (int i = 0; i < BOARD_WIDTH; i++) {
      Board next = new Board(b);
      if (next.move(tileSequence, directions[i])) {
        Board candidate = solve_dfs(next, depthLimit, depth + 1);
        if (candidate == null && next.finished()) {
          candidate = next;
        }
        if (candidate != null) {
          if (candidate.finished()) {
            updateBest(candidate);
          } else {
            int score = evaluate(candidate);
            if (score > best_score) {
              best_score = score;
              best = candidate;
            }
          }
        }
      }
    }
    return best;
  }