gistfile1.java

  static int[] array;

  @BeforeClass
  public static void prepare() {
    array = new int[]{
            1, 3, 5, 7, 9,
            11, 13, 15, 17, 19,
            21, 23, 25, 27, 29,
            31, 33, 35, 37, 39,
            41, 43, 45, 47, 49,
            1, 3, 5, 7, 9,
            11, 13, 15, 17, 19,
            21, 23, 25, 27, 29,
            31, 33, 35, 37, 39,
            41, 43, 45, 22, 11
    };
  }

  boolean valid1(int[] array) {
    long x = 0;
    for (int j : array) {
      if (j < 25 && (x & (1 << (j << 1))) != 0) {
        return true;
      }
      if (((j & 1) == 0) && ((x & (1 << (j >> 1))) != 0)) {
        return true;
      }
      x |= 1 << j;
    }
    return false;
  }

  boolean valid2(int[] array) {
    int[] bits = new int[50];
    for (int j : array) {
      if (j < 25 && bits[j*2] != 0) {
        return true;
      }
      if (j % 2 == 0 && bits[j/2] != 0) {
        return true;
      }
      bits[j] = 1;
    }
    return false;
  }

  @Test
  public void solution1() {
    int max = 100000000;

    long start2 = System.currentTimeMillis();
    for (int i = 0; i < max; i++) {
      assertTrue(valid2(array));
    }
    long end2 = System.currentTimeMillis();
    System.out.println("2: " + (end2 - start2));

    long start = System.currentTimeMillis();
    for (int i = 0; i < max; i++) {
      assertTrue(valid1(array));
    }
    long end = System.currentTimeMillis();
    System.out.println("1: " + (end - start));
  }