排列组合算法

// 阶乘
function factorial($n) {
    return array_product(range(1, $n));
}

// 排列数
function A($n, $m) {
    return factorial($n)/factorial($n-$m);
}

// 组合数
function C($n, $m) {
    return A($n, $m)/factorial($m);
}

// 排列
function arrangement($a, $m) {
    $r = array();

    $n = count($a);
    if ($m <= 0 || $m > $n) {
        return $r;
    }

    for ($i=0; $i<$n; $i++) {
        $b = $a;
        $t = array_splice($b, $i, 1);
        if ($m == 1) {
            $r[] = $t;
        } else {
            $c = arrangement($b, $m-1);
            foreach ($c as $v) {
                $r[] = array_merge($t, $v);
            }
        }
    }

    return $r;
}

// 组合
function combination($a, $m) {
    $r = array();

    $n = count($a);
    if ($m <= 0 || $m > $n) {
        return $r;
    }

    for ($i=0; $i<$n; $i++) {
        $t = array($a[$i]);
        if ($m == 1) {
            $r[] = $t;
        } else {
            $b = array_slice($a, $i+1);
            $c = combination($b, $m-1);
            foreach ($c as $v) {
                $r[] = array_merge($t, $v);
            }
        }
    }

    return $r;
}


// ====== 测试 ======
$a = array("A", "B", "C", "D");

$r = arrangement($a, 2);
var_dump($r);

$r = A(4, 2);
echo $r."\n";

$r = combination($a, 2);
var_dump($r);

$r = C(4, 2);
echo $r."\n";

以上代码摘自：CSDN博主「song5198038_1」
原文链接：blog.csdn.net/song5198038_1/articl...

多组数组所有的组合
比如一个商品有三个属性，计算出该商品的所有SKU
颜色：红色、黄色 | 尺寸：M、L、XL | 重量：轻、重

function getCombinationToString($val)
{
    // 保存上一个的值
    static $res = array();
    if(empty($res))
    {
        $res = $val;
    }else{
        // 临时数组保存结合的结果
        $list = array();
        foreach ($res as $k => $v) {
            foreach ($val as $key => $value) {
               $list[$k.'_'.$key] = $v.'_'.$value;
            }
        }
        $res = $list;
    }
    return $res;
}

$A = ['红色','黄色'];
$B = ['M','L','XL'];
$C = ['轻','重'];

// 先将各属性值处理成一个整体
$list['A'] = $A;
$list['B'] = $B;
$list['C'] = $C;

$res = array();
foreach ($list as $k => $v) {
    $res = getCombinationToString($v);
}

//得到结果
array(12) {
  ["0_0_0"] => string(12) "红色_M_轻"
  ["0_0_1"] => string(12) "红色_M_重"
  ["0_1_0"] => string(12) "红色_L_轻"
  ["0_1_1"] => string(12) "红色_L_重"
  ["0_2_0"] => string(13) "红色_XL_轻"
  ["0_2_1"] => string(13) "红色_XL_重"
  ["1_0_0"] => string(12) "黄色_M_轻"
  ["1_0_1"] => string(12) "黄色_M_重"
  ["1_1_0"] => string(12) "黄色_L_轻"
  ["1_1_1"] => string(12) "黄色_L_重"
  ["1_2_0"] => string(13) "黄色_XL_轻"
  ["1_2_1"] => string(13) "黄色_XL_重"
}

以上代码摘自：开源博客「18y的个人空间」
原文链接：my.oschina.net/18y/blog/3043088

本作品采用《CC 协议》，转载必须注明作者和本文链接