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         if (s == null || s.length()==0) { 4                 return 0; 5         } 6         Map
     
       m = new HashMap
      
       (); 7         m.put('I', 1); 8         m.put('V', 5); 9         m.put('X', 10);10         m.put('L', 50);11         m.put('C', 100);12         m.put('D', 500);13         m.put('M', 1000);14 15         int length = s.length();16         int result = m.get(s.charAt(length - 1));17         for (int i = length - 2; i >= 0; i--) {18             if (m.get(s.charAt(i + 1)) <= m.get(s.charAt(i))) {19                 result += m.get(s.charAt(i));20             } else {21                 result -= m.get(s.charAt(i));22             }23         }24         return result;25     }26 }27 28 // 方法二29 public class Solution {30     /**31      * @param s Roman representation32      * @return an integer33      */34     public int romanToInt(String s) {35         // Write your code here36         int ans;37         char[] sc = s.toCharArray();38         ans = toInt(sc[0]);                        //0 special39         for (int i = 1; i < s.length(); i++) {40             ans += toInt(sc[i]);41             if (toInt(sc[i - 1]) < toInt(sc[i])) {42                 ans -= toInt(sc[i - 1]) * 2;43             }44         }45         return ans;46     }47 48     int toInt(char s) {49         switch(s) {50             case 'I':return 1;51             case 'V':return 5;52             case 'X':return 10;53             case 'L':return 50;54             case 'C':return 100;55             case 'D':return 500;56             case 'M':return 1000;57         }58         return 0;59     }60 }