[leetcode:13] 罗马数字转十进制

竟然过了

class Solution {
public:
int romanToInt(string s) {
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 res = m[s[s.size() - 1]];
for (int i = s.size() - 2; i >= 0; --i) {
if (m[s[i + 1]] > m[s[i]]) {
res -= m[s[i]];
} else {
res += m[s[i]];
}
}
return res;
}
};