leetcode_c++：Compare Version Numbers(165)

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

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class Solution {private:    // get number from ver[pos] into num    void getNum(const string &version, int &len, int &pos, int &num) {        num = 0;        while (pos < len && version[pos] != '.') {            num = num * 10 + version[pos] - '0';            pos++;        }        pos++;    }public:    int compareVersion(string version1, string version2) {        int len1 = version1.length();        int len2 = version2.length();        int curPos1 = 0, curPos2 = 0;        int num1, num2;        while (curPos1 < len1 || curPos2 < len2) {            getNum(version1, len1, curPos1, num1);            getNum(version2, len2, curPos2, num2);            if (num1 > num2)                return 1;            if (num1 < num2)                return -1;        }        return 0;    }};