Leetcode: Roman to Integer, Integer to Roman

Roman to Integer

Integer to Roman 

这两题纯粹是模拟题，关键就是理解罗马计数，直接上代码吧

class Solution {

public:

    int romanToInt(string s) {

         int result = 0;

         for (int i = 0; i < s.size(); ++i) {

             if (i > 0 && map(s[i]) > map(s[i-1])) {

                 result += (map(s[i]) - 2 * map(s[i-1]));

             } else {

                 result += map(s[i]);

             }

         }

         return result;

    }

    

    inline int map(const char c) {

        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;

            default  : return 0;

        }

    }

};

 

class Solution {

public:

    string intToRoman(int num) {

        const int radix[] = {1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1};

        const string symbol[] = {"M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"};

        string roman;

        for (int i = 0; num > 0; ++i) {

            int count = num / radix[i];

            num %= radix[i];

            for (; count > 0; --count) {

                roman += symbol[i];

            }

        }

        return roman;

    }

};