Compare Version Numbers

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Compare two version numbers version1 and version1.
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


這題還是蠻有意思的，就是版本號碼之間的比較，剛開始沒考慮到例如1.6.5與1.6之間的比較，沒有想到用遞迴的方法，解決起來就比較困難了。。

public class Solution {    public int compareVersion(String version1, String version2) {                if(version1.equals(version2)){            return 0;        }                int first1,first2;        String second1,second2;        if(version1.contains(".")){            String[] str=version1.split("\\.",2);            first1=Integer.parseInt(str[0]);            second1=str[1];        }        else{            first1=Integer.parseInt(version1);            second1="0";        }                if(version2.contains(".")){            String[] str=version2.split("\\.",2);            first2=Integer.parseInt(str[0]);            second2=str[1];        }        else{            first2=Integer.parseInt(version2);            second2="0";        }                        if(first1>first2){            return 1;        }        else if(first1<first2){            return -1;        }                else return compareVersion(second1,second2);    }}

 

Compare Version Numbers