LeetCode Roman to Integer 罗马数字转阿拉伯数字

Roman to Integer

Given a roman numeral, convert it to an integer.

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

知道转换规律就行。

int romanToInt(string s) {
		if (s.length()==0) return 0;

		map<char, int> m;
		m['I'] = 1;
		m['V'] = 5;
		m['X'] = 10;
		m['L'] = 50;
		m['C'] = 100;
		m['D'] = 500;
		m['M'] = 1000;

		int n = s.length();
		int result = m[s[n-1]];
		for (int i=n-2; i>=0; i--) {
			if (m[s[i+1]] <= m[s[i]])
				result += m[s[i]];
			else
				result -= m[s[i]];
		}
		return result;
	}