13. 罗马数字转整数c

int romanToInt(char* s) {
    int n=strlen(s);
    int c[26];
    c['I'-'A']=1;
    c['V'-'A']=5;
    c['X'-'A']=10;
    c['L'-'A']=50;
    c['C'-'A']=100;
    c['D'-'A']=500;
    c['M'-'A']=1000;
    int sum=0;
    for(int i=0;i<n;i++){
        if(i<n-1 && c[s[i]-'A']<c[s[i+1]-'A']){
            sum-=c[s[i]-'A'];
        }else{
            sum+=c[s[i]-'A'];
        }
    }       
    return sum;
}

结果：