[LC] 165. Compare Version Numbers

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"

Solution 1:

class Solution {
    public int compareVersion(String version1, String version2) {
        if (version1 == null || version2 == null) {
            return 0;
        }
        String[] strArr1 = version1.split("\\.");
        String[] strArr2 = version2.split("\\.");
        int index = 0;
        while (index < strArr1.length && index < strArr2.length) {
            int cur_str1 = Integer.parseInt(strArr1[index]);
            int cur_str2 = Integer.parseInt(strArr2[index]);
            if (cur_str1 < cur_str2) {
                return -1;
            } else if (cur_str1 > cur_str2) {
                return 1;
            }
            index += 1;
        }

        if (index < strArr1.length) {
            for (int i = index; i < strArr1.length; i++) {
                if (Integer.parseInt(strArr1[i]) > 0) {
                    return 1;
                }
            }
        }
        if (index < strArr2.length) {
            for (int j = index; j < strArr2.length; j++) {
                if (Integer.parseInt(strArr2[j]) > 0) {
                    return -1;
                }
            }
        }
        return 0;
    }
}

Solution 2:

class Solution {
    public int compareVersion(String version1, String version2) {
        String[] strArr1 = version1.split("\\.");
        String[] strArr2 = version2.split("\\.");
        int len = Math.max(strArr1.length, strArr2.length);
        for (int i = 0; i< len; i++) {
            int cur_str1 = i >= strArr1.length ? 0 : Integer.parseInt(strArr1[i]);
            int cur_str2 = i >= strArr2.length ? 0 : Integer.parseInt(strArr2[i]);
            if (cur_str1 < cur_str2) {
                return -1;
            } else if (cur_str1 > cur_str2) {
                return 1;
            }
        }
        return 0;
    }
}