LeetCode:Compare Version Numbers

问题描述：

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：

1、将字符串转存；

2、将字符串分割成两部分；

3、将字符串的前半部转变成整数比较大小，如果相等，则比较后面大小。

JAVA代码：

public class Solution {    public int compareVersion(String version1, String version2) {        if(version1 == null || version2 == null){            return 0;        }        int i = 0;        String [] s1 = version1.split("\\.");        String [] s2 = version2.split("\\.");        int len1 = s1.length;        int len2 = s2.length;        while(i < len1 || i < len2){            int x1 = i < len1 ? Integer.parseInt(s1[i]):0;            int x2 = i < len2 ? Integer.parseInt(s2[i]):0;            if(x1 < x2){                return -1;            }else if(x1 > x2){                return 1;            }else{                ++i;            }        }        return 0;    }}