165. Compare Version Numbers

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

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

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class Solution {public:    int compareVersion(string v1, string v2) {        int i=0;        int j=0;        for(;i<v1.size()||j<v2.size();++i,++j)        {            int sum1=0;            int sum2=0;            for(;i<v1.size()&&v1[i]!='.';++i)            sum1=sum1*10+(v1[i]-'0');            for(;j<v2.size()&&v2[j]!='.';++j)            sum2=sum2*10+(v2[j]-'0');            if(sum1<sum2) return -1;            if(sum2<sum1) return 1;                    }        return 0;    }};