Leetcode-Integer to Roman

class Solution {
public:
	int romanToInt(string s) {
	// IMPORTANT: Please reset any member data you declared, as
	// the same Solution instance will be reused for each test case.
	int result=0;  
		
	map<char,int> roman;  
	roman['I']=1;  
	roman['V']=5;  
	roman['X']=10;  
	roman['L']=50;  
	roman['C']=100;  
	roman['D']=500;  
	roman['M']=1000;  
		
	for(int i=s.length()-1;i>=0;i--)  
	{  
		if(i==s.length()-1)  
		{  
		result=roman[s[i]];  
		continue;  
		}  
		if(roman[s[i]] >= roman[s[i+1]])  
		result+=roman[s[i]];  
		else  
		result-=roman[s[i]];  
	}  
	return result;  
	}
};