最优匹配

best_match.php

<?php

$rand = [20,15,10,6];
$r = 39;
function combination($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;
}

$sets = [];

for ($i=1,$j=count($rand);$i<$j;$i++){
    foreach(combination($rand, $i) as $v) {
        $sets[implode(',',$v)] = abs($r - array_sum($v));
    }
}

asort($sets);
echo "序列:".implode(',', $rand).", 匹配:{$r}\n";
echo "最优: ".key($sets).", 误差: ".current($sets)."\n";
print_r($sets);