生成伪均匀分布的随机序列

PHP+Uniform+Rand+Serial.php

<?php
/**
 * Rang = [$start, $end]
 */
function gen_rand_serial($count, $start, $end)
{
    $R     = $end - $start + 1;
    $count = min($R, $count);

    if ($R == $count) {
        for ($i = $start; $i < $end + 1; $i++) {
            $res[] = $i;
        }
    } else {
        $f = floor($R / $count);

        $N       = $count;
        $reverse = $f == 1;

        if ($reverse) {
            $N = $R - $count;
            $f = floor($R / $N);
        }

        for ($i = 0; $i < $N; ++$i) {
            $min   = min($start + $i * $f, $end);
            $max   = min($start + ($i + 1) * $f - 1, $end);

            if ($i == $N - 1) {
                $max = max($max, $end);
            }

            $res[] = mt_rand($min, $max);

            echo "(" . $min . "-" . $max . ")\n";
        }

        if ($reverse) {
            $new_res = array();
            for ($i = $start; $i <= $end; ++$i) {
                if (!in_array($i, $res)) {
                    $new_res[] = $i;
                }
            }
            $res = $new_res;
        }
    }

    return $res;
}

array_shift($argv);
if (count($argv) < 3) {
    echo "Parameters illegal\n";
    print_r($argv);
} else {
    $res = gen_rand_serial((int) $argv[0], (int) $argv[1], (int) $argv[2]);
    if ($res) {
        print_r($res);
    } else {
        echo "Error! Res = " . json_encode($res) . "\n";
    }
}