php序号发生器，数字重组，可以隐藏原来的1，2，3。。。

一个晚上的成果，原理：

将1,2,3,4,5,6,7,8,9,0映射到9,5,1,0,4,8,7,3,2,6

同理映射base,base有1-10种数组，也就是可以一位数到10位数

$base 实际上是下面的根据下面数组处理得来的。

array(
array(0),
array(1,0),
array(2,0,1),
array(3,0,2,1),
array(4,0,1,3,2),
array(5,1,0,4,3,2),
array(6,2,0,4,5,1,3),
array(7,3,0,4,6,2,1,5),
array(8,4,0,1,5,7,3,2,6),
array(9,5,1,0,4,8,7,3,2,6)
);

参数$num是种子数，$m是结果位数，$offset一个偏移值（可以更有效的打乱数字）。

function seq10($num, $m, $offset = 0) {
    static $seq = array(9,5,1,0,4,8,7,3,2,6);
    static $base = array(
        array(1,10),
        array(10,1,100),
        array(100,1,10,1000),
        array(1000,1,100,10,10000),
        array(10000,1,10,1000,100,100000),
        array(100000,10,1,10000,1000,100,1000000),
        array(1000000,100,1,10000,100000,10,1000,10000000),
        array(10000000,1000,1,10000,1000000,100,10,100000,100000000),
        array(100000000,10000,1,10,100000,10000000,1000,100,1000000,1000000000),
        array(1000000000,100000,10,1,10000,100000000,10000000,1000,100,1000000,10000000000)
    );
    $res = $num;
    for ($i = 0; $i < 16; $i++) {
        $num = 0;
        for ($j = 0; $j < $m; $j++) {
            $num += $seq[$res % 10] * $base[$m-1][$j];
            $res /= 10;
        }
        $res = ($num + $offset + $i) % $base[$m-1][$m];
    }
    return $res;
}

通过调用上面的函数，便可以进行任意数字映射，如1-100映射结果到1-100

$arr = array();
$start = microtime(true);
for ($i = 1; $i < 100; $i++) $arr[$i] = seq10($i, 2, 12);
$end = microtime(true);
print_r($arr);
echo count($arr)."\n";
echo $end - $start;

结果:
E:\>php seq.php
Array
(
    [1] => 8
    [2] => 88
    [3] => 16
    [4] => 75
    [5] => 0
    [6] => 58
    [7] => 70
    [8] => 91
    ...
    [90] => 29
    [91] => 51
    [92] => 66
    [93] => 23
    [94] => 62
    [95] => 54
    [96] => 22
    [97] => 3
    [98] => 34
    [99] => 72
)
99
0.002357006072998

1-10映射到6位数

$arr = array();
$start = microtime(true);
for ($i = 1; $i < 10; $i++) $arr[$i] = seq10($i, 6, 123456);
$end = microtime(true);
print_r($arr);
echo count($arr)."\n";
echo $end - $start;

E:\>php seq.php
Array
(
    [1] => 721627
    [2] => 782511
    [3] => 256581
    [4] => 969508
    [5] => 451505
    [6] => 928354
    [7] => 302664
    [8] => 387627
    [9] => 817626
)
9
0.00050187110900879

唯一性验证：

$arr = array();
$start = microtime(true);
for ($i = 0; $i < 1000000; $i++) $arr[seq10($i, 6, 123456)] = 1;
$end = microtime(true);
//print_r($arr);
echo count($arr)."\n";
echo $end - $start;

E:\>php seq.php
1000000
36.970967054367