Given a roman numeral, convert it to an integer.

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

请参考上一篇博文：

<a target=_blank href=http://www.mamicode.com/"http://blog.csdn.net/chenxun_2010/article/details/43274049">http://blog.csdn.net/chenxun_2010/article/details/43274049

class Solution {
public:
	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;
		}
	}
	int romanToInt(string s) {
		int result = 0;
		for (size_t 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;
	}
};

leetcode.13---------Roman to Integer