PHP实现bitmap位图排序与求交集的方法

function sort()
{
    // var_dump(PHP_INT_MAX, PHP_INT_SIZE);
    // int 9223372036854775807
    // int 8
    $bitmap = array_fill(0, 50, 0); //申请一个整形数组, 50个元素, 初始化为整数0
    $int_bit_size = PHP_INT_SIZE * 8; //$bitmap中每个整形的二进制位数 (本例中int = 8*8 = 64bit; $bitmap数组一共50*64 = 3200个bit位),也就是说能为最大值小于等于3200的整数集合排序
    $a = array(1,4,3,50,34,60,100,88,200,150,300); //定义一个乱序的数组
    //扫描$a中的每一个数, 将其转换为 x*64 + y
    foreach ($a as $k => $v) {
      $shang = $v / $int_bit_size;
      $yushu = $v % $int_bit_size;
      $offset = 1 << $yushu;
      $bitmap[$shang] = $bitmap[$shang] | $offset;//将bit位置为1
    }
    //将$bitmap中的bit位依次还原为整数输出,即可得到排序后的数组
    $b = array();
    foreach ($bitmap as $k => $v) {
      for ($i = 0; $i < $int_bit_size; $i++) {
        $tmp = 1 << $i;
        $flag = $tmp & $bitmap[$k];
        // $b[] = $flag ? $k * $int_bit_size + $i : false;
        if ($flag) {
          $b[] = $k * $int_bit_size + $i;
        }
      }
    }
    var_dump($b);exit;
}

public function sort($a = array())
{
    // var_dump(PHP_INT_MAX, PHP_INT_SIZE);
    // int 9223372036854775807
    // int 8
    $bitmap = array_fill(0, 50, 0); //申请一个整形数组, 50个元素, 初始化为整数0
    $int_bit_size = PHP_INT_SIZE * 8; //$bitmap中每个整形的二进制位数 (本例中int = 8*8 = 64bit; $bitmap数组一共50*64 = 3200个bit位)
    // $a = array(1,4,3,50,34,60,100,88,200,150,300); //定一个乱序的数组
    //扫描$a中的每一个数, 将其转换为 x*64 + y
    foreach ($a as $k => $v) {
      $shang = $v / $int_bit_size;
      $yushu = $v % $int_bit_size;
      $offset = 1 << $yushu;
      $bitmap[$shang] = $bitmap[$shang] | $offset;//将bit位置为1
    }
    return $bitmap;
  }
  public function intersect()
  {
    $int_bit_size = PHP_INT_SIZE * 8;
    $a = array(1,4,3,50,34,60,100,88,200,150,300);
    $b = array(1,5,3,50,34,55,100,87,222,150,300);
    $bit_a = $this->sort($a);
    $bit_b = $this->sort($b);
    $c = array();
    foreach ($bit_a as $k => $v) {
      $c[$k] = $bit_a[$k] & $bit_b[$k]; //二进制 & 计算求交集
    }
    $d = array();
    foreach ($c as $k => $v) {
      for ($i = 0; $i < $int_bit_size; $i++) {
        $tmp = 1 << $i;
        $flag = $tmp & $c[$k];
        // $b[] = $flag ? $k * $int_bit_size + $i : false;
        if ($flag) {
          $d[] = $k * $int_bit_size + $i;
        }
      }
    }
    var_dump($d);exit;
}