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

思路：按照"."分割开，然后从头开始对应比较大小。
转义字符需要加\\. http://swiftlet.net/archives/709

public class Solution {
    public int compareVersion(String version1, String version2) {
    if(version1==null||version2==null)
    {
        return 0;
    }
    String[] change1=version1.split("\\.");
    String[] change2=version2.split("\\.");
    
    for(int i=0,j=0;i<change1.length||j<change2.length;)
    {
        int v1=i<change1.length?Integer.parseInt(change1[i]):0;
        int v2=j<change2.length?Integer.parseInt(change2[j]):0;
        if(v1>v2)
        {
            return 1;
        }
        else if(v1<v2)
        {
            return -1;
        }
        i++;
        j++;
    }
    return 0;
        }

    }