Compare Version Numbers

最新推荐文章于 2024-08-02 16:45:34 发布

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最新推荐文章于 2024-08-02 16:45:34 发布

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分类专栏： Two pointers

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本文详细解释了如何比较两个版本号，并提供了相应的算法实现。包括版本号的解析、比较规则及示例应用。

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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.

You may assume the default revision number for each level of a version number to be 0. For example, version number 3.4 has a revision number of 3 and 4 for its first and second level revision number. Its third and fourth level revision number are both 0.

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

Example 4:

Input: version1 = "1.01", version2 = "1.001"
Output: 0
Explanation: Ignoring leading zeroes, both “01” and “001" represent the same number “1”

Example 5:

Input: version1 = "1.0", version2 = "1.0.0"
Output: 0
Explanation: The first version number does not have a third level revision number, which means its third level revision number is default to "0"

Note:

Version strings are composed of numeric strings separated by dots . and this numeric strings may have leading zeroes.
Version strings do not start or end with dots, and they will not be two consecutive dots.

思路：split注意是“\\.”，剩下的就跟merge two sorted list一样，同样的指针同时走；

class Solution {
    public int compareVersion(String version1, String version2) {
        if(version1.equals(version2)) {
            return 0;
        }
        String[] splits1 = version1.split("\\.");
        String[] splits2 = version2.split("\\.");
        int i = 0;
        while(i < splits1.length || i < splits2.length) {
            if(i < splits1.length && i < splits2.length) {
                int n1 = Integer.parseInt(splits1[i]);
                int n2 = Integer.parseInt(splits2[i]);
                if(n1 > n2) {
                    return 1;
                } else if(n1 < n2) {
                    return -1;
                }
            } else if(i < splits1.length) {
                if(Integer.parseInt(splits1[i]) != 0) {
                    return 1;
                }
            } else if(i < splits2.length) {
                if(Integer.parseInt(splits2[i]) != 0) {
                    return -1;
                }
            }
            i++;
        }
        return 0;
    }
}