问题链接

Roman to Integer | LeetCode OJ

问题描述

把一个罗马数字转换为普通数字。

解决办法

public class Solution {
    public int romanToInt(String s) {
        int lastCharNumber = 0;
        int result = 0;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            int currentCharNumber = romanCharToInt(c);
            if(lastCharNumber < currentCharNumber){
                result -= lastCharNumber;
                result += (currentCharNumber - lastCharNumber);
            }
            else{
                result += currentCharNumber;
            }
            lastCharNumber = currentCharNumber;
        }
        return result;
    }
    
    public static int romanCharToInt(char c) throws NumberFormatException {
        switch (c) {
            case 'I':
                return 1;
            case 'V':
                return 5;
            case 'X':
                return 10;
            case 'L':
                return 50;
            case 'C':
                return 100;
            case 'D':
                return 500;
            case 'M':
                return 1000;
        }
        throw new NumberFormatException("Illegal char " + String.valueOf(c));
    }
}