基于P站(Poloniex)的广度优先搜索算法来获得任意两种币的兑换价格

[
    {
        "symbol": "BTS_BTC",
        "price": "0.0000000186",
        "time": 1731852313035,
        "dailyChange": "-0.0462",
        "ts": 1731852313054
    },
    {
        "symbol": "DASH_BTC",
        "price": "0.000317",
        "time": 1731848096481,
        "dailyChange": "0.0063",
        "ts": 1731848096489
    },
    ... ...
]

const fetch = require('node-fetch');
 
async function getTicker(a, b) {
  try {
    const response = await fetch('https://api.poloniex.com/markets/price');
    const data = await response.json();
 
    // 创建一个哈希表来存储代币对及其价格
    const pairMap = new Map();
 
    // 使用直接对及其反向对填充哈希表
    for (const { symbol, price } of data) {
      const [base, quote] = symbol.split('_').map(token => token.toLowerCase());
      if (!pairMap.has(base)) pairMap.set(base, new Map());
      if (!pairMap.has(quote)) pairMap.set(quote, new Map());
      
      pairMap.get(base).set(quote, parseFloat(price));
      pairMap.get(quote).set(base, 1 / parseFloat(price)); // 添加反向边
    }
 
    // 将 token 转换为小写
    a = a.toLowerCase();
    b = b.toLowerCase();
 
    // BFS 查找从 a 到 b 的转换率
    const queue = [[a, 1]]; // 从初始代币和兑换率 1 开始
    const visited = new Set([a]);
 
    while (queue.length > 0) {
      const [currentToken, currentRate] = queue.shift();
 
      if (currentToken === b) return currentRate;
 
      // Check connected tokens
      for (const [nextToken, rate] of (pairMap.get(currentToken) || new Map())) {
        if (!visited.has(nextToken)) {
          visited.add(nextToken);
          queue.push([nextToken, currentRate * rate]);
        }
      }
    }
 
    // 如果未找到路径，则返回 null
    return null;
  } catch (error) {
    console.error("获取或处理数据时出错:", error);
    return null;
  }
}
 
// Example usage:
(async () => {
  const rate = await getTicker('btc', 'trx');
  console.log('BTC 到 TRX 的兑换率:', rate);
})();

const fetch = require('node-fetch');
 
async function getToken(pairs) {
  try {
    const response = await fetch('https://api.poloniex.com/markets/price');
    const data = await response.json();
 
    // 创建一个哈希表来存储代币对及其价格
    const pairMap = new Map();
 
    // 使用直接对及其反向对填充哈希表
    for (const { symbol, price } of data) {
      const [base, quote] = symbol.split('_').map(token => token.toLowerCase());
      if (!pairMap.has(base)) pairMap.set(base, new Map());
      if (!pairMap.has(quote)) pairMap.set(quote, new Map());
      
      pairMap.get(base).set(quote, parseFloat(price));
      pairMap.get(quote).set(base, 1 / parseFloat(price)); // 添加一条反向边
    }
 
    // 使用 BFS 查找单个对的转换率的辅助函数
    const findConversionRate = (a, b) => {
      a = a.toLowerCase();
      b = b.toLowerCase();
      
      if (a === b) return 1; // 直接转换
 
      const queue = [[a, 1]];
      const visited = new Set([a]);
 
      while (queue.length > 0) {
        const [currentToken, currentRate] = queue.shift(); // 出队列
 
        if (currentToken === b) return currentRate;
 
        for (const [nextToken, rate] of (pairMap.get(currentToken) || new Map())) {
          if (!visited.has(nextToken)) {
            visited.add(nextToken);
            queue.push([nextToken, currentRate * rate]);
          }
        }
      }
 
      return null; // 路径没找到
    };
 
    // 迭代列表并查找转换率
    const results = pairs.map(([a, b]) => findConversionRate(a, b));
    return results;
  } catch (error) {
    console.error("Error fetching or processing data:", error);
    return pairs.map(() => null); // 如果有错误，则返回每对的 null
  }
}
 
// Example usage:
(async () => {
  const conversionRates = await getToken([['btc', 'trx'], ['usd', 'steem']]);
  console.log('兑换结果：', conversionRates);
})();