Compare two version numbers version1 and version2.
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
Solution：类似于split的方法把字符串解析, 遇到'.'就判断之前的sum1和sum2
class Solution {
public:
int compareVersion(string version1, string version2) {
int sum1=,sum2=;
int n1=version1.size(),n2=version2.size();
for(int i=,j=;i<n1||j<n2;i++,j++){
while(i<n1&&version1[i]!='.'){
sum1=sum1*+version1[i]-'';
i++;
}
while(j<n2&&version2[j]!='.'){
sum2=sum2*+version2[j]-'';
j++;
}
if(sum1>sum2)return ;
else if(sum1<sum2)return -;
else{
sum1=;
sum2=;
}
}
return ;
}
};