Roman to integer.cpp

using namespace std; 
int value(char r){ 
	if (r == 'I') 
		return 1; 
	if (r == 'V') 
		return 5; 
	if (r == 'X') 
		return 10; 
	if (r == 'L') 
		return 50; 
	if (r == 'C') 
		return 100; 
	if (r == 'D') 
		return 500; 
	if (r == 'M') 
		return 1000; 
	return -1; 
} 
int romanToDecimal(string &str) {
	int res = 0; 
	for (int i=0; i<str.length(); i++){ 
		// Getting value of symbol s[i] 
		int s1 = value(str[i]); 
		if (i+1 < str.length()) { 
			int s2 = value(str[i+1]); 
			if (s1 >= s2) { 
				res = res + s1; 
			} 
			else{ 
				res = res + s2 - s1; 
				i++; 
			} 
		} 
		else{ 
			res = res + s1;
		} 
	} 
	return res; 
} 
int main() { 
	int t;
	cin>>t;
	while(t--){
	   string str ;
	cin>>str;
	cout <<romanToDecimal(str) << endl;  
	}
	return 0; 
}