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.

class Solution {   
    public int compareVersion(String version1, String version2) {
       
        String[] versionArray1 = version1.split("\\.");
        String[] versionArray2 = version2.split("\\.");        

        int len1 = versionArray1.length;
        int len2 = versionArray2.length;
        int len = len1 <= len2 ? len1 : len2;

        //共有版本号部分，从前向后比较对应位置数字
        int x1, x2;
        for (int i = 0; i < len; i++) {
            x1 = Integer.parseInt(versionArray1[i]);
            x2 = Integer.parseInt(versionArray2[i]);
            if (x1 > x2) {
                return 1;
            } else if (x1 < x2) {
                return -1;
            }
        }
        
        //共有版本号相等的情况下，谁的版本号段数更多且多余部分不全为0，谁的版本更新
        if (len1 > len2) {
            for (int i = len; i < len1; i++) {
                if (Integer.parseInt(versionArray1[i]) > 0) {
                    return 1;
                }
            }
        } else if (len1 < len2) {
            for (int i = len; i < len2; i++) {
                if (Integer.parseInt(versionArray2[i]) > 0) {
                    return -1;
                }
            }
        }
        
        return 0;
    }
}
  class Solution {   
    public int compareVersion(String version1, String version2) {
       
        version1 = version1 + ".";
        version2 = version2 + ".";
        int l1 = version1.length();
        int l2 = version2.length();
        int i=0, j=0, v1, v2;
        while(i<l1 || j<l2) {
            if (i < l1) {
                int x1 = version1.indexOf('.', i);
                v1 = Integer.parseInt(version1.substring(i, x1));
                i = x1+1;
            } else {
                v1 = 0;
            }
            
            if (j < l2) {
                int x2 = version2.indexOf('.', j);
                v2 = Integer.parseInt(version2.substring(j, x2));
                j = x2+1;
            } else {
                v2 = 0;
            }
            
            if(v1 < v2) {
                return -1;
            } else if (v1 > v2) {
                return 1;
            }
        }
        return 0;
    }
}
class Solution {   
    public int compareVersion(String v1, String v2) {
        int p1 = 0;
        int p2 = 0;
        
        while(p1 < v1.length() || p2 < v2.length()){
            int e1 = getNextChunk(p1, v1);
            int e2 = getNextChunk(p2, v2);
            
            int c1 = 0;
            int c2 = 0;
            if(e1 != p1) c1 = Integer.parseInt(v1.substring(p1, e1));
            if(e2 != p2) c2 = Integer.parseInt(v2.substring(p2, e2));
            
            if(c1 != c2) return c1 > c2 ? 1 : -1;
            
            p1 = ++e1;
            p2 = ++e2;
        }
        
        return 0;
    } 
    
    int getNextChunk(int start, String str){
        while(start < str.length() && str.charAt(start) != '.'){
            start++;
        }
        return start;
    }   
}