【LeetCode】13.罗马数字转整数

class Solution {
public:
    int romanToInt(string s) {
        int ans=0;
        unordered_map<char,int> mp;
        mp['I']=1;
        mp['V']=5;
        mp['X']=10;
        mp['L']=50;
        mp['C']=100;
        mp['D']=500;
        mp['M']=1000;
        int i=0;
        for(i;i<s.size()-1;i++){
            if(s[i]=='I'){
                if(s[i+1]=='V') {
                    ans+=4;
                    i++;
                    continue;
                }
                if(s[i+1]=='X'){
                    ans+=9;
                    i++;
                    continue;
                }
            }
            if(s[i]=='X'){
                if(s[i+1]=='L') {
                    ans+=40;
                    i++;
                    continue;
                }
                if(s[i+1]=='C'){
                    ans+=90;
                    i++;
                    continue;
                }
            }
            if(s[i]=='C'){
                if(s[i+1]=='D') {
                    ans+=400;
                    i++;
                    continue;
                }
                if(s[i+1]=='M'){
                    ans+=900;
                    i++;
                    continue;
                }
            }
            ans+=mp[s[i]];
        }
        return ans+mp[s[i]];
    }
};