力扣13. 罗马数字转整数

Posted 2021-06-17 幽殇默

题目地址

class Solution {
public:
    int romanToInt(string s) {
        int ans=0;
        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;
        ans+=mp[s[0]];
        for(int i=1;i<s.size();i++)
        {
            if(mp[s[i-1]]<mp[s[i]]) ans+=mp[s[i]]-2*mp[s[i-1]];//之前加了一次，还得再减一次
            else ans+=mp[s[i]];
        }
        return ans;
    }
};

class Solution {
public:
    int romanToInt(string s) {
        int ans=0;
        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;
        for(int i=0;i<s.size();i++)
        {
            if(mp[s[i]]<mp[s[i+1]]&&(i+1)<s.size()) ans-=mp[s[i]];
            else ans+=mp[s[i]];
        }
        return ans;
    }
};