Roman to Integer

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.

 

 1 public class Solution {

 2     public int romanToInt(String s) {

 3         // Start typing your Java solution below

 4         // DO NOT write main() function

 5         StringBuffer ss = new StringBuffer(s);

 6         int i,j;

 7         int result = 0;

 8         if(ss.length() == 0) return result;

 9         else if(ss.length() == 1) return romanChar(ss.charAt(0)); 

10         for(i = 0; i < ss.length(); i++){

11             j = i + 1;

12             if(j == ss.length()){

13                 result += romanChar(ss.charAt(i));

14                 break;

15             }

16             if(leftLarger(ss.charAt(i),ss.charAt(j))){

17                 result += romanChar(ss.charAt(i));

18             }

19             else{

20                 result += romanChar(ss.charAt(j)) - romanChar(ss.charAt(i));

21                 i ++;

22                 

23             }

24         }

25         return result;

26     }

27     

28     public int romanChar(char c){

29         if(c == 'I') return 1;

30         else if(c == 'V') return 5;

31         else if(c == 'X') return 10;

32         else if(c == 'L') return 50;

33         else if(c == 'C') return 100;

34         else if(c == 'D') return 500;

35         else if(c == 'M') return 1000;

36         else return -1;

37     }

38     public boolean leftLarger(char a,char b){

39         if(a == 'M') return true;

40         if(a == 'D' && b != 'M') return true;

41         else if(a == 'C' && b != 'M' && b != 'D') return true;

42         else if(a == 'L' && b != 'M' && b != 'D' && b != 'C') return true;

43         else if(a == 'X' && b != 'M' && b != 'L' && b != 'D' && b != 'C' ) return true;

44         else if(a == 'V' && b != 'M' && b != 'X' && b != 'L' && b != 'D' && b != 'C') return true;

45         else if(a == 'I' && b == 'I') return true;

46         else return false;

47     }

48 }