leetcode Roman to Integer

#include <iostream>
#include <map>
#include <string>
using namespace std;

int romanToInt(string s){
    int length = s.length();
    if (length < 1) return 0;
    map<int,int> romanMap;
    romanMap[‘I‘] = 1;      romanMap[‘V‘] = 5;
    romanMap[‘X‘] = 10;     romanMap[‘L‘] = 50;
    romanMap[‘C‘] = 100;    romanMap[‘D‘] = 500;
    romanMap[‘M‘] = 1000;
    int index = length - 1 , sum = romanMap[s[index]];
    while (--index >= 0) {
        if (romanMap[s[index+1]] >romanMap[s[index]]) sum -= romanMap[s[index]];
        else sum += romanMap[s[index]];
    }
    return sum;
}

int main(){
    cout<<romanToInt("DCXXI")<<endl;
    return 0;
}