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

Solution：依次对比

思路：依次分别提取出Version1, Version2的每一子版本号作比较(‘.’作为分隔符），直到某一子版本号不相等 或到 最后(相等)

Solution Code：

public class Solution {
    public int compareVersion(String version1, String version2) {
        String[] version1_num = version1.split("\\.");
        String[] version2_num = version2.split("\\.");

        int length = Math.max(version1_num.length, version2_num.length);
        for (int i = 0; i < length; i++) {
            Integer v1_num = i < version1_num.length ? Integer.parseInt(version1_num[i]) : 0;
            Integer v2_num = i < version2_num.length ? Integer.parseInt(version2_num[i]) : 0;
            int compare = v1_num.compareTo(v2_num);
            if (compare != 0) {
                return compare;
            }
        }
        return 0;
    }
}