public class RomanToInteger {

public int romanToInt(String s) {

int len = s.length();

int n = 0;

for (int i = len - 1; i >= 0; i--) {

char c = s.charAt(i);

switch (c) {

case 'V': n += 5; break;

case 'L': n += 50; break;

case 'D': n += 500; break;

case 'I': n += (n >= 5 ? -1 : 1); break;

case 'X': n += (n >= 50 ? -10 : 10); break;

case 'C': n += (n >= 500 ? -100 : 100); break;

case 'M': n += 1000; break;

}

}

return n;

}

}