takto nejako:

Kód:
<?php

$pA = $argv[1]; // 0.75
$pB = $argv[2]; // 0.25

$bestof = $argv[3]; // 7
$nwin = round($bestof/2 + 0.5);

$s=0;
while($s<1<<$bestof) {
    $prob = 1;
    $wA = $wB = 0;
    for($i=$bestof-1; $i>=0 && $wA<$nwin && $wB<$nwin; $i--) {
        $res = ($s>>$i)&1;
        $prob *= $res ? ($i%2==0 ? $pA : 1-$pB) : ($i%2==0 ? 1-$pA : $pB);
        if($res) $wA++; else $wB++;
    }
    $sres[$wA.":".$wB] += $prob;
    if($wA>$wB) $probA += $prob;
    $s += 1<<($bestof-$wA-$wB);
}

var_dump($sres);

echo "$probA\n";

?>