美元、加元、1.3 的输出错误；美元、英镑，0.71；美元，日元，109；英镑、日元，预期 155 预期 110.5，但正在接近-1.0

Question

import java.io.*;
import java.math.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws IOException {
        InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
        BufferedReader in = new BufferedReader(reader);
    
        // Create a map of exchange rates
        Map<String, Double> fxRates = new HashMap<>();
        fxRates.put("USD, JPY", 109.0);
        fxRates.put("USD, GBP", 0.71);
        fxRates.put("GBP, JPY", 155.0);
        fxRates.put("CAD, CNY", 5.27);
        fxRates.put("CAD, KR", 921.0);
        fxRates.put("USD, CAD", 1.3);
        fxRates.put("CAD, JPY", 88.0);
    
        // Read the input and calculate the maximum amount of the target currency
        // that can be obtained from 1 unit of the selected currency
        String line;
        double maxAmount = -1.0;
        while ((line = in.readLine()) != null) {
            String[] currencies = line.split(";");
            for (String currencyPair : currencies) {
                String[] currencies = currencyPair.trim().split(",");
                if (currencies.length == 2) {
                    String originalCurrency = currencies[0].trim();
                    String targetCurrency = currencies[1].trim();
                    double amount = calculateMaxAmount(fxRates, targetCurrency, originalCurrency, 1);
                    if (amount > maxAmount) {
                        maxAmount = amount;
                    }
                }
            }
        }
    
        // Print the maximum amount
        System.out.println(maxAmount);
    }
    
    public static double calculateMaxAmount(Map<String, Double> fxRates, String originalCurrency, String targetCurrency, double amount) {
        if (originalCurrency.equals(targetCurrency)) {
            return amount;
        }
    
        double maxAmount = -1.0;
        for (Map.Entry<String, Double> entry : fxRates.entrySet()) {
            String[] currencies = entry.getKey().split(",");
            String fromCurrency = currencies[0].trim();
            String toCurrency = currencies[1].trim();
            double rate = entry.getValue();
    
            if (fromCurrency.equals(originalCurrency)) {
                double newAmount = amount * rate;
                double tempMaxAmount = calculateMaxAmount(fxRates, toCurrency, targetCurrency, newAmount);
                if (tempMaxAmount > maxAmount) {
                    maxAmount = tempMaxAmount;
                }
            }
        }
    
        return maxAmount;

}
}

任何人都可以让我知道我的代码有什么问题吗？

预期 110.5，但实际结果为 1.0。您提供的输入应该是：

Answer 1

“...任何人都可以让我知道我的代码有什么问题吗？

预期为 110.5，但实际为 1.0。 ...”

calculateMaxAmount有一个递归调用。

if (fromCurrency.equals(originalCurrency)) {
    double newAmount = amount * rate;
    double tempMaxAmount = calculateMaxAmount(fxRates, toCurrency, targetCurrency, newAmount);
    if (tempMaxAmount > maxAmount) {
        maxAmount = tempMaxAmount;
    }
}

与main方法类似，只要大于当前值就赋值。

if (!fromCurrency.equals(originalCurrency)) {
    double newAmount = amount * rate;
    if (newAmount > maxAmount) maxAmount = newAmount;
}

这是输入和输出的示例。

USD,GBP
155.0