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leetcode笔记:Integer to Roman

2015-09-19 12:36 本站整理 浏览(93)
一.题目描述
Given a roman numeral, convert it to an integer.
Input is guaranteed to be within the range from 1 to 3999.
二.题目分析
罗马数字总结:
1~9: {“I”, “II”, “III”, “IV”, “V”, “VI”, “VII”, “VIII”, “IX”};
10~90: {“X”, “XX”, “XXX”, “XL”, “L”, “LX”, “LXX”, “LXXX”, “XC”};
100~900: {“C”, “CC”, “CCC”, “CD”, “D”, “DC”, “DCC”, “DCCC”, “CM”};
1000~3000: {“M”, “MM”, “MMM”}.
关于罗马数制可参考:http://baike.baidu.com/view/1246899.htm
这个问题就是输入个阿拉伯数字,将其转换为罗马数字字符串。
该题可使用最简单的操作,即取数字的低位到高位进行操作。每次取一位,取完一位则数字除10,取出的那一位数字则用罗马数字表示出来。需要注意的是如果当前位不是原数字的各位则需要扩大10倍或者100倍等。
三.示例代码
class Solution {
public:
    string intToRoman(int num) {
        string str;  
        string symbol[]={"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};  
        int value[]=    {1000,900,500,400, 100, 90,  50, 40,  10, 9,   5,  4,   1}; 
        for(int i=0;num!=0;++i)
        {
            while(num>=value[i])
            {
                num-=value[i];
                str+=symbol[i];
            }
        }
        return str;
    }
};

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