Currency Exchange Algorithm

Implement a currency exchange algorithm that reads exchange rates between currencies and calculates the optimal conversion path from one currency to another. The input is a series of currency pairs with their exchange rates, in the format [from, to, rate]. Output the maximum convertible amount from the start currency to the target currency. Provide a complete code solution. Example Input [[['USD', 'EUR', 0.9], ['EUR', 'JPY', 120.0], ['USD', 'GBP', 0.75]], 'USD', 'JPY']