leetcode Integer to Roman

原创于 2014-10-29 17:01:32 发布 · 306 阅读

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本文介绍了一种使用C++编程语言实现整数到罗马数字转换的方法，通过定义类和辅助函数，实现从整数到罗马数字的精确转换。

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代码

class Solution {
public:
    string intToRoman(int num) {
        if(num<1||num>3999)
            return "";
            
        int digit = 1000;
        vector<int> digits;
        
        while(digit>0)
        {
            digits.push_back(num/digit);
            num %= digit;
            digit /= 10;
        }
        
        string res = "";
        res += intToRomanHelper(digits[0], 'M', ' ', ' ');
        res += intToRomanHelper(digits[1], 'C', 'D', 'M');
        res += intToRomanHelper(digits[2], 'X', 'L', 'C');
        res += intToRomanHelper(digits[3], 'I', 'V', 'X');
        return res;
    }
    
    string intToRomanHelper(int digit, char one, char five, char ten)
    {
        string temp = "";
        
        switch(digit)
        {
            case 9:
                temp += one;
                temp += ten;
                break;
            case 8:
            case 7:
            case 6:
            case 5:
            temp += five;
            for(int i = 5; i < digit; ++i)
                temp += one;
            break;
            case 4:
            temp += one;
            temp += five;
            break;
            case 3:
            case 2:
            case 1:
            for(int i = 0; i < digit; ++i)
                temp += one;
            break;
            default:
            break;
        }
        
        return temp;
        
    }
};