165 Compare Version Numbers

Compare two version numbers version1 and version1.
If version1 > version2 return 1, if version1 < version2 return -1, otherwise return 0.

You may assume that the version strings are non-empty and contain only digits and the . character.
The . character does not represent a decimal point and is used to separate number sequences.
For instance, 2.5 is not "two and a half" or "half way to version three", it is the fifth second-level revision of the second first-level revision.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.37

class Solution {
public:
    int compareVersion(string version1, string version2) {
        int pos1=0;
        int pos2=0;
        int token1=getToken(version1,pos1);
        int token2=getToken(version2,pos2);
        while((pos1<version1.size() || pos2<version2.size()) && token1==token2)
        {   
            token1=getToken(version1,pos1);
            token2=getToken(version2,pos2);
        }
        if (token1==token2)
            return 0;
        if (token1>token2)
            return 1;
        return -1;
    }
    int getToken(string &version,int &pos)
    {
        if (pos>=version.size())
            return 0;
        int res=0;
        while(pos<version.size() && version[pos]!='.')
        {
            res = res*10+version[pos]-'0';
            pos++;
        }
        if (version[pos]=='.')
            pos++;
        return res;
    }
};