165. Compare Version Numbers

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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:

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0.1 < 1.1 < 1.2 < 13.37

解法1：

应该算简单题。要注意的一点是java里string.split(regex), 如果是特殊字符比如”.”的时候，要注意escape。然后每一位比较，如果有一个字符串比较短，就把他对应的位看成是0。
C++

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Java

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public class Solution {
    public int compareVersion(String version1, String version2) {
        String[] v1 = version1.split("\\.");
        String[] v2 = version2.split("\\.");
        for (int i =  0; i < Math.max(v1.length, v2.length); i++) {
             int v1number = i < v1.length ? Integer.parseInt(v1[i]) : 0;
            int v2number = i < v2.length ? Integer.parseInt(v2[i]) : 0;
            if (v1number > v2number) {
                return 1;
            } else if (v1number < v2number) {
                return -1;
            }
        }
        return 0;
    }
}