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Compare Version Numbers

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

注意一个特例: 1 和 1.0。

所以 在比较完对应的位数之后,还要查看多的位数是不是均为0.

还有就是在split(".") 时候,由于.是正则表达式中的符号,所以要转置。
 1 public class Solution { 2     public int compareVersion(String version1, String version2) { 3         String[] parts1 = version1.split("\\."); 4         String[] parts2 = version2.split("\\."); 5         int len1 = parts1.length; 6         int len2 = parts2.length; 7         int i = 0; 8         for(; i < len1 && i < len2; i ++){ 9             if(Integer.valueOf(parts1[i]) > Integer.valueOf(parts2[i])) return 1;10             if(Integer.valueOf(parts2[i]) > Integer.valueOf(parts1[i])) return -1;11         }12         if(len1 > len2){13             while(i < len1){14                 if(Integer.valueOf(parts1[i++]) != 0) return 1;15             }16         }else if(len1 < len2){17             while(i < len2){18                 if(Integer.valueOf(parts2[i++]) != 0) return -1;19             }20         }21         return 0;22     }23 }

 

Compare Version Numbers