业务需求 nuls_bx 交易对牟定盘口做市
但是要求牟定 bx_usdt 主流交易对, 真实晕 写了个递归 经过测试可用 转换路径如下
nuls_btc btc_usdt bx_eth eth_usdt 经过 四个交易对 转换成目标交易对 汇率

<?php

// 都需要对标  bx_usdt

$symbol = 'nuls_coin';
$benchmarkSymbolList = ['nuls_btc' , 'btc_usdt', 'coin_usdt'];

$benchmarkData = [

    'nuls_btc' => [
        '0.00015635',
        '0.00015832',
    ],
    // 'coin_btc' => [
    //     '0.00000278',  // 买
    //     '0.00002329', // 卖 
    // ],

    'btc_usdt' => [
        '3995.00',
        '3998.01',
    ],
    'coin_usdt' => [
        '0.0924',
        '0.1926',
    ]
   
];


// $symbol = 'eos_bx';
// $benchmarkSymbolList = ['eos_usdt', 'bx_usdt'];

// $benchmarkData = [

//     'eos_usdt' => [
//         3.6627,
//         3.6549
//     ],
//     'bx_usdt' =>[
//         0.1022,
//         0.1011
//     ]
// ];

/**
 * @des 交易对检测函数
 * @param $symbol
 * @param $checkSymbolList
 * @return bool
 * ------------------------------------------------------------
 */
function checkSymbolList($symbol, $checkSymbolList)
{
    list($coinFrom, $coinTo) = explode('_', $symbol);

    $coinList = [];
    foreach ($checkSymbolList as $checkSymbol) {

        list($cFrom, $cTo) = explode('_', $checkSymbol);

        $coinList[$cFrom] = isset($coinList[$cFrom]) ? $coinList[$cFrom] + 1 : 1;
        $coinList[$cTo] = isset($coinList[$cTo]) ? $coinList[$cTo] + 1 : 1;
    }

    // 目标币对 仅可以出现一个
    if (empty($coinList[$coinFrom]) || $coinList[$coinFrom] != 1 || empty($coinList[$coinTo]) || $coinList[$coinTo] != 1) {
        return false;
    }

    unset($coinList[$coinFrom], $coinList[$coinTo]);

    // 除目标币种 外 其他币种最少出现两次
    if (max($coinList) != 2 || min($coinList) != 2) {
        return false;
    }

    return true;
}

/**
 * @des 调用递归
 * @param $symbol
 * @param $benchmarkSymbolList
 * @param $benchmarkData
 * @return array
 * ------------------------------------------------------------
 */
function integrateRateToBenchMarkPrice($symbol, $benchmarkSymbolList, $benchmarkData)
{
    // 选择对标方向
    list($coinFrom, $coinTo) = explode('_', $symbol);

    // 效验交易对是否正确
    if (!checkSymbolList($symbol, $benchmarkSymbolList)) return [];

    return rateSymbolConversion($coinFrom, $coinTo, $benchmarkSymbolList, $benchmarkData);
}

/**
 * @des 多交易对汇率转换 递归
 * @param $coinFrom
 * @param $coinTo
 * @param $benchmarkSymbolList
 * @param $benchmarkData
 * @param array $params
 * @return array
 * ------------------------------------------------------------
 */
function rateSymbolConversion($coinFrom, $coinTo, $benchmarkSymbolList, $benchmarkData, $params = [])
{
    // 容错 异常跳出递归
    if (!$benchmarkSymbolList) return $params;

    // 转换后数据 nuls_usdt
    $askConversion = $params[0] ?? 0;
    $bidConversion = $params[1] ?? 0;
    $conversionCoin = $params[2] ?? '';

    // 交易对排序
    foreach ($benchmarkSymbolList as $k => $benchmarkSymbol) {

        list($from, $to) = explode('_', $benchmarkSymbol);

        // 提取交易对
        list($bidBenchmark, $askBenchmark) = $benchmarkData[$benchmarkSymbol];
 
        if ($conversionCoin == $from) {
            unset($benchmarkSymbolList[$k]);
            $askNewBenchmark = bcmul($askConversion, $askBenchmark, 10);
            $bidNewBenchmark = bcmul($bidConversion, $bidBenchmark, 10);

            echo $benchmarkSymbol ,' => from ', $conversionCoin,PHP_EOL;

            return rateSymbolConversion($coinFrom, $coinTo, $benchmarkSymbolList, $benchmarkData, [$bidNewBenchmark, $askNewBenchmark, $to]);
        } else if ($conversionCoin == $to) {

            unset($benchmarkSymbolList[$k]);

            echo $benchmarkSymbol ,' => to ', $conversionCoin, PHP_EOL;

            echo 'askBenchmark =>',$askConversion,' ', $askBenchmark, ' bidBenchmark => ', $bidConversion,' ', $bidBenchmark, PHP_EOL;

            $askNewBenchmark = bcdiv($askConversion, $bidBenchmark, 10);
            $bidNewBenchmark = bcdiv($bidConversion, $askBenchmark, 10);
 
            return rateSymbolConversion($coinFrom, $coinTo, $benchmarkSymbolList, $benchmarkData, [$bidNewBenchmark, $askNewBenchmark, $from]);
        }

        // 判断当前交易对 为代币 所在代币交易对
        if ($coinFrom == $from) {

            // 第一次 参数为空 直接复制 调用递归
            if (!$params) {
                // 注销使用过的数组元素
                unset($benchmarkSymbolList[$k]);

                echo $benchmarkSymbol ,' => null ', $coinFrom, PHP_EOL;

                return rateSymbolConversion($coinFrom, $coinTo, $benchmarkSymbolList, $benchmarkData, [$bidBenchmark, $askBenchmark, $to]);
            }

        }
    }

    return $params;
}

$data = integrateRateToBenchMarkPrice($symbol, $benchmarkSymbolList, $benchmarkData);
var_export($data);

localhost:Desktop admin$ php test.php 

# 执行顺序
nuls_btc => null nuls
btc_usdt => from btc
bz_usdt => to usdt
askBenchmark =>0.6324884000 0.1926 bidBenchmark => 0.6250888635 0.0924
array (
  0 => '3.2455288862',
  1 => '6.8451125541',
  2 => 'coin',
)