Compare Version Numbers --- LeetCode

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

解題思路：以“.”爲分隔符將版本號分爲字符串數組，然後將兩個數組中從下標爲0開始的字符串進行比較。

public class Solution {
    
       public int compare(String v1,String v2){
while(v1.startsWith("0")&&v1.length()>1){
v1=v1.substring(1);
}
while(v2.startsWith("0")&&v2.length()>1){
v2=v2.substring(1);
} 
int len1=v1.length();
int len2=v2.length();
if(len1>len2){
return 1;
}
if(len1<len2){
return -1;
}
for(int i=0;i<len1;i++){
  char ch1=v1.charAt(i);
  char ch2=v2.charAt(i);
  if(ch1>ch2){
  return 1;
  }
  if(ch1<ch2){
  return -1;
  }
}
return 0;
}
   
    public int compareVersion(String version1, String version2) {    
    String [] v1=version1.split("\\.");
    String [] v2=version2.split("\\."); 
        int v1Len=v1.length;
        int v2Len=v2.length;
        int len=v1Len<=v2Len?v1Len:v2Len;
        int i=0;
        for(;i<len;i++){
           int rs=compare(v1[i],v2[i]);
           if(rs!=0){
          return rs;
           }
        }        
        if(v1Len>v2Len){
           for(;i<v1Len;i++){
          if(Integer.valueOf(v1[i])!=0){
          return 1; 
          }
           }
        }
        if(v1Len<v2Len){
           for(;i<v2Len;i++){
          if(Integer.valueOf(v2[i])!=0){
          return -1;
          }
           }
        }
        return 0;    
    }
    
}