Exemplo n.º 1
0
  public static void main(String[] args) throws IOException {
    BufferedReader bufferedReader = new BufferedReader(new FileReader(new File("islands.in")));
    PrintWriter printWriter = new PrintWriter(new File("islands.out"));

    int N = Integer.parseInt(bufferedReader.readLine());

    int landscape[] = new int[N];

    for (int i = 0; i < N; i++) {
      landscape[i] = Integer.parseInt(bufferedReader.readLine());
    }

    for (int i = 0; i < N; i++) {
      int prev, next, current = landscape[i];

      if (i == 0) {
        prev = next = landscape[i + 1];
      } else if (i == N - 1) {
        prev = next = landscape[i - 1];
      } else {
        prev = landscape[i - 1];
        next = landscape[i + 1];
      }

      if (prev < current && next < current) {
        if (!tops.containsKey(current)) tops.put(current, new LinkedList<Top>());
        Top newTop = new Top();
        if (Bottom.lastBottom != null) {
          newTop.left = Bottom.lastBottom;
          Bottom.lastBottom.right = newTop;
        }
        tops.get(current).add(newTop);
        Top.lastTop = newTop;
      } else if (prev > current && next > current) {
        if (!bottoms.containsKey(current)) bottoms.put(current, new LinkedList<Bottom>());
        Bottom newBottom = new Bottom();
        if (Top.lastTop != null) {
          newBottom.left = Top.lastTop;
          Top.lastTop.right = newBottom;
        }
        bottoms.get(current).add(newBottom);
        Bottom.lastBottom = newBottom;
      } else if (prev > current && next == current) {
        while (i < N - 1 && landscape[i + 1] == current) {
          i++;
        }
        if (i == N - 1 || landscape[i + 1] > current) {

          if (!bottoms.containsKey(current)) bottoms.put(current, new LinkedList<Bottom>());
          Bottom newBottom = new Bottom();
          if (Top.lastTop != null) {
            newBottom.left = Top.lastTop;
            Top.lastTop.right = newBottom;
          }
          bottoms.get(current).add(newBottom);
          Bottom.lastBottom = newBottom;
        }
      } else if (prev < current && next == current) {
        while (i < N - 1 && landscape[i + 1] == current) {
          i++;
        }
        if (i == N - 1 || landscape[i + 1] < current) {

          if (!tops.containsKey(current)) tops.put(current, new LinkedList<Top>());
          Top newTop = new Top();
          if (Bottom.lastBottom != null) {
            newTop.left = Bottom.lastBottom;
            Bottom.lastBottom.right = newTop;
          }
          tops.get(current).add(newTop);
          Top.lastTop = newTop;
        }
      }
    }

    Arrays.sort(landscape);

    int maxActive = 0;

    int prev = 0;
    for (int i : landscape) {
      if (i != prev) {
        if (bottoms.containsKey(i))
          for (Bottom b : bottoms.get(i)) {
            if (b.right != null) b.right.activate();
            if (b.left != null) b.left.activate();
          }
        if (tops.containsKey(i))
          for (Top t : tops.get(i)) {
            t.sink();
          }
        maxActive = Math.max(maxActive, Top.totalActive);
      }
    }

    printWriter.println(maxActive);
    printWriter.flush();
  }