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;}