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

给定两个非空字符串，里面包含数字和‘ . ’，代表着不同的版本号，让我们判断版本的高低。我们可以用split方法把字符串通过' . '进行分割，得到两个字符串数组，然后依次比较相同位置代表数字的大小。代码如下：

public class Solution {
    public int compareVersion(String version1, String version2) {
        String[] s1 = version1.split("\\.");
        String[] s2 = version2.split("\\.");
        int i = 0;
        for(i = 0; i < s1.length && i < s2.length; i++) {
            if(Integer.parseInt(s1[i]) != Integer.parseInt(s2[i])) 
                return Integer.parseInt(s1[i]) > Integer.parseInt(s2[i]) ? 1 : -1;
        }
        for(; i < s1.length; i++) {
            if(Integer.parseInt(s1[i]) != 0)
                return 1;
        }
        for(; i < s2.length; i++) {
            if(Integer.parseInt(s2[i]) != 0)
                return -1;
        }
        return 0;
    }
}