Roman to Integer--LeetCode

1.题目

Roman to Integer

2.代码

class Solution {public:    int romanToInt(string s) {        int res = 0;        unordered_map<char, int> m{{'I', 1}, {'V', 5}, {'X', 10}, {'L', 50}, {'C', 100}, {'D', 500}, {'M', 1000}};        for (int i = 0; i < s.size(); ++i)         {            int val = m[s[i]];            if (i == s.size() - 1 || m[s[i+1]] <= m[s[i]])                 res += val;            else                 res -= val;        }        return res;    }};