我目前正在经历一个伟大的老脑放屁并且动态地选择下一轮的获胜者将进入的下一个“回合比赛”:

上面的梯子是动态生成的，我想做的是找出下一个匹配 ID。我目前已经将其作为 POC，但如果竞争阶梯达到 64 或更多，这是不可持续的:

$ar = [
 1 => [
     ['id' => 1,'name' => 'round1, pair 1'],
     ['id' => 2,'name' => 'round1, pair 2'],
     ['id' => 3,'name' => 'round1, pair 3'],
     ['id' => 4,'name' => 'round1, pair 4'],
 ],
 2 => [
     ['id' => 5,'name' => 'round2, pair 1'],
     ['id' => 6,'name' => 'round2, pair 2'],
 ]
];

$cases = [0, 0, 1, 1, 2, 2];

foreach($ar as $i => $round) {

    foreach($round as $_i => $r) {
        echo $r['name'] . " & NEXT_MATCH_ID::> " . $ar[($i + 1)][$cases[$_i]]['id'] . "<br /> ";
    }
}

例如，是否有更简单的方法来实现上述内容而无需硬编码变量 ($cases)。

本质上，“匹配/对”的数量减半，阶梯为:4 -> 2 -> 1。

上面生成了正确的 ID，但它不是可扩展的或动态的；

round1, pair 1 & NEXT_MATCH_ID::> 5
round1, pair 2 & NEXT_MATCH_ID::> 5
round1, pair 3 & NEXT_MATCH_ID::> 6
round1, pair 4 & NEXT_MATCH_ID::> 6
round2, pair 1 & NEXT_MATCH_ID::> ...
round2, pair 2 & NEXT_MATCH_ID::> ...
//......etc etc...

Demo/ Example如果需要，上面的代码。

注意事项

• “球员/球队”比赛没有限制，这可以是指数级的，4, 6, 8, 10, 12, 14, 16, 18....32, 34...64。 ..等.
• 这永远不会发生/适用于最后一轮(总决赛 - 1 比赛)，因为没有进一步的轮次可以晋级。 (很容易受到 if($i == count($rounds)) {.... do not continue... 的限制。
• 有可能同时进行多场比赛，因此“下一轮 ID”不能是lastId + 1。

最佳答案

只是数学

请记住，每一轮都包含 pow(2, Rounds - Round + 1) 团队和 pow(2, Rounds - Round) 比赛。只需将其总结为几何级数即可。

在回合 $round 之前进行的比赛数是 geometric progression 2^(rounds-1) + 2^(rounds-2) + ... 2^(rounds - round + 1) a=2^(rounds-1)，r=1/2，n=round-1。它的总和是 2^(rounds) - 2^(rounds+1-round)。

因此匹配 ID 和下一个匹配 ID 只是三个参数的函数:pairnum、round、rounds。我将其计算移到了函数 getMatchId 和 getNextId 中。

示例

<?php
// just matchesInPreviousRounds + parnum
function getMatchId($pairnum, $round, $rounds) {
    // matchesInPreviousRounds - is a sum of a geometric progression  
    // 2^(rounds-1) + 2^(rounds-2) + ... 2^(rounds - round + 1) 
    // with a=2^(rounds-1), r=1/2, n = round-1
    // its sum is 2^(rounds) - 2^(rounds+1-round)
    $inPreviousRounds = $round > 1 ?  (pow(2, $rounds) - pow(2, $rounds + 1 - $round)) : 0;

    $id = $inPreviousRounds + $pairnum;

    return (int)$id;
}

// next id is last id of a round + half a pairnum.
function getNextId($pairnum, $round, $rounds) {
    if($round === $rounds) {
        return false;
    }

    $matchesInThisAndPreviousRounds = pow(2, $rounds) - pow(2, $rounds - $round);

    $nextid = $matchesInThisAndPreviousRounds + ceil($pairnum / 2);

    return (int)$nextid;
}

$divide = 64; // for 1/64 at the start
$power = round(log($divide) / log(2)); // get 6 for 64
$rounds = (int) $power + 1;


for($round = 1; $round <= $rounds; $round++) {
    // every round contains 2^($rounds - $round + 1) of teams 
    // and has 2^($rounds - $round) of matches
    $teamsLeft = pow(2, $rounds - $round + 1);
    $pairsLeft = pow(2, $rounds - $round);


    for($pairnum = 1; $pairnum <= $pairsLeft; $pairnum++) {
        $id = getMatchId($pairnum, $round, $rounds);
        $nextid = getNextId($pairnum, $round, $rounds);

        echo "Round $round, pair $pairnum, id $id ";
        echo "winner goes to " . $nextid ? $nextid : "A BAR" . "\n";
    }
}

其结果

Round 1, pair 1, id 1, winner goes to 65
Round 1, pair 2, id 2, winner goes to 65
...
Round 1, pair 62, id 62, winner goes to 95
Round 1, pair 63, id 63, winner goes to 96
Round 1, pair 64, id 64, winner goes to 96
Round 2, pair 1, id 65, winner goes to 97
Round 2, pair 2, id 66, winner goes to 97
...
Round 2, pair 29, id 93, winner goes to 111
Round 2, pair 30, id 94, winner goes to 111
Round 2, pair 31, id 95, winner goes to 112
Round 2, pair 32, id 96, winner goes to 112
Round 3, pair 1, id 97, winner goes to 113
Round 3, pair 2, id 98, winner goes to 113
...
Round 3, pair 13, id 109, winner goes to 119
Round 3, pair 14, id 110, winner goes to 119
Round 3, pair 15, id 111, winner goes to 120
Round 3, pair 16, id 112, winner goes to 120
Round 4, pair 1, id 113, winner goes to 121
Round 4, pair 2, id 114, winner goes to 121
...
Round 4, pair 7, id 119, winner goes to 124
Round 4, pair 8, id 120, winner goes to 124
Round 5, pair 1, id 121, winner goes to 125
Round 5, pair 2, id 122, winner goes to 125
Round 5, pair 3, id 123, winner goes to 126
Round 5, pair 4, id 124, winner goes to 126
Round 6, pair 1, id 125, winner goes to 127
Round 6, pair 2, id 126, winner goes to 127
Round 7, pair 1, id 127, winner goes to A BAR

关于php - 动态获取/排序下一个多维数组元素，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42239239/