将罗马数字转换为整数

Question

我正在关注的罗马数字到整数转换器：

https://www.selftaughtjs.com/algorithm-sundays-converting-roman-numerals/

我尝试将 Javascript 函数转换为 Java：

public class RomanToDecimal {

public static void main (String[] args) {

    int result = 0;

    int[] decimal = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};

    String[] roman = {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};

    // Test string, the number 895

    String test = "DCCCXCV";

    for (int i = 0; i < decimal.length; i++ ) {

        while (test.indexOf(roman[i]) == 0) {

            result += decimal[i];

            test = test.replace(roman[i], "");

        }

    }

    System.out.println(result);

}

}

输出是615，这是不正确的。

请帮助我理解我哪里出错了。

Answer 1

您test = test.replace(roman[i], "");将所有出现的“C”替换为“”，因此在找到第一个“C”并将总数加 100 后，您将消除所有剩余的“C”，并且从不计算它们。因此，您实际上计算了 的值"DCXV"，即615。您应该只替换roman[i]起始索引为 0 的出现，您可以通过替换来实现：test = test.replace(roman[i], "");和：test = test.substring(roman[i].length()); // this will remove the first 1 or 2 characters&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; // of test, depending on the length of roman[i]以下：int result = 0;int[] decimal = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};String[] roman = {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};// Test string, the number 895String test = "DCCCXCV";for (int i = 0; i < decimal.length; i++ ) {&nbsp; &nbsp; while (test.indexOf(roman[i]) == 0) {&nbsp; &nbsp; &nbsp; &nbsp; result += decimal[i];&nbsp; &nbsp; &nbsp; &nbsp; test = test.substring(roman[i].length());&nbsp; &nbsp; }}System.out.println(result);印刷：895

Answer 2

test = test.replace(roman[i], "");这将替换每次出现。相反，您应该只截断字符串开头（位置 0）的出现。尝试使用substring而不是替换，并将长度作为参数传递roman[i]