leetCode练习（165）

题目：Compare Version Numbers

难度：medium

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.

Example 1:

Input: version1 = "0.1", version2 = "1.1"
Output: -1

Example 2:

Input: version1 = "1.0.1", version2 = "1"
Output: 1

Example 3:

Input: version1 = "7.5.2.4", version2 = "7.5.3"
Output: -1

解题思路：

常规解法，将版本号根据"."划分为多段，依次比较即可。注意，使用spit函数的时候，正则表达式对'.'号需要使用转义字符。另外，要注意末尾是0的情况。

代码如下：

public static int compareVersion(String version1, String version2) {
		int res=0;
		String[] v1 = version1.split("\\.");
        String[] v2 = version2.split("\\.");
        for(int i=0;i0) return 1;
                else return 0;
        	}
        }
        int l1 = v1.length;
        int l2 = v2.length;
        if(l1>l2){
        	for(int i=l2;i0) return 1;
        	}
        	return 0;
        }else if(l10) return -1;
        	}
        	return 0;
        }else return 0;
    }