Roman to Integer

最新推荐文章于 2022-07-21 15:19:09 发布

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最新推荐文章于 2022-07-21 15:19:09 发布

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分类专栏： Leetcode

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本文介绍了一种将罗马数字转换为整数的算法实现。输入保证在1到3999范围内，通过解析罗马数字的构成规律进行转换。

Question:

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.

Solution:

public class Solution {
    public int romanToInt(String s) {
        int sum = 0;
        s = "AA" + s;
        int len = s.length();
        int sub = 0;
        
        
        for(int i = len-1; i>1; i--){
            if(chartoInt(s.charAt(i)) == 0)
                break;
            
            sum += chartoInt(s.charAt(i));
            
            if(chartoInt(s.charAt(i-1)) >= chartoInt(s.charAt(i))){
                ;
            }
            
            else{
                sub += chartoInt(s.charAt(--i));
            }
        }
        
        return sum-sub;
        
        
    }
    
    public int chartoInt(char c){
        int i =0;
        switch(c){
            case 'I':
                i = 1;
                break;
            case 'V':
                i = 5;
                break;
            case 'X':
                i = 10;
                break;
            case 'L':
                i = 50;
                break;
            case 'C':
                i = 100;
                break;
            case 'D':
                i = 500;
                break;
            case 'M':
                i = 1000;
                break;
            case 'A':
                i=0;
                break;
            default:
                break;
        }
        return i;
    }
}