leetcode21: Integer to Roman

最新推荐文章于 2019-09-24 16:08:00 发布

原创最新推荐文章于 2019-09-24 16:08:00 发布 · 545 阅读

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CC 4.0 BY-SA版权

本文提供了一种使用C++实现的方法，将整数转换为罗马数字。通过定义一个常量数组来映射整数到罗马数字，并使用循环逐步构建最终的罗马数字字符串。

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Given an integer, convert it to a roman numeral.

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

my reminders: string is different vector, which can use position instead of iterator to assign a element. because string's element is char but vector is templete. also string can insert or operate char*, char and string as arguments.

class Solution {
public:
    string intToRoman(int num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        
        const char* table[4][10] =
        {
            "", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX",
            "", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC",
            "", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM",
            "", "M", "MM", "MMM", "  ", " ", "  ", "   ", "    ", "  "
        };
        
        if( num < 0 || num >3999) return "";
        
        int digit = 0;
        string rel;
        while( num  != 0) {
            rel.insert( 0,  table[digit++][ num%10] );
            num /=10;
        }
        
        return rel;
        
    }
};