Given a roman numeral, convert it to an integer. Input is guaranteed to be within the range from 1 to 3999.

LeetCode-Roman to Integer

C++:
class Solution {
public:
    int romanToInt(string s) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int ret=0;
        for(int i=0;i<s.size();i++){
            if(i<s.size()-1){
                if(getVal(s[i])<getVal(s[i+1])) ret -=getVal(s[i]);
                else ret +=getVal(s[i]);
            }else ret +=getVal(s[i]);
        }
        return ret;
    }
    int getVal(char c){
        switch(c){
            case 'I':
                return 1;
            case 'V':
                return 5;
            case 'X':
                return 10;
            case 'L':
                return 50;
            case 'C':
                return 100;
            case 'D':
                return 500;
            case 'M':
                return 1000;
    		default:
				return 0;
        }
    }
};
Java:
public class Solution {
    public int romanToInt(String s) {
        // Start typing your Java solution below
        // DO NOT write main() function
        int ret=0;
        for(int i=0;i<s.length();i++){
            if(i<s.length()-1){
                if(getVal(s.charAt(i))<getVal(s.charAt(i+1))) ret -=getVal(s.charAt(i));
                else ret +=getVal(s.charAt(i));
            }else ret +=getVal(s.charAt(i));
        }
        return ret;
    }
    public int getVal(char c){
        switch(c){
            case 'I':
                return 1;
            case 'V':
                return 5;
            case 'X':
                return 10;
            case 'L':
                return 50;
            case 'C':
                return 100;
            case 'D':
                return 500;
            case 'M':
                return 1000;
            default:
                return 0;
        }
    }
}