LeetCode-Roman to Integer

Given a roman numeral, convert it to an integer.

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

Solution:

Code:

<span style="font-size:14px;">class Solution {
public:
    int getRomanValue(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;  
        } 
    }
        
    int romanToInt(string s) {
        const int length = s.size();
        if (length == 0) return 0;
        int lastV = getRomanValue(s[0]);
        int subResult = lastV;
        int result = 0;
        int value;
        for (int i = 1; i < length; ++i) {
            value = getRomanValue(s[i]);
            if (value == lastV) subResult+= value;
            else if (value < lastV) {
                result += subResult;
                lastV = value;
                subResult = lastV;
            } else {
                subResult = value-subResult;
                lastV = value;
            }
        }
        result += subResult;
        return result;
    }
};</span>