# 165. Compare Version Numbers

[Link](https://leetcode.com/problems/compare-version-numbers/description/)

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:**

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

**Solution**

沒什麼好說的，直接split去比較，位數不足就補0。

```
 public int compareVersion(String version1, String version2) {
        String[] version1s = version1.split("\\.");
        String[] version2s = version2.split("\\.");
        int maxLength = Math.max(version1s.length, version2s.length);
        int fromVersion1 = 0;
        int fromVersion2 = 0;
        for(int i = 0; i < maxLength; i ++){
            if(version2s.length-1 < i){
                fromVersion2 = 0;
            }else{
                fromVersion2 = Integer.parseInt(version2s[i]);
            }
            
            if(version1s.length-1 < i){
                fromVersion1 = 0;
            }else{
                fromVersion1 = Integer.parseInt(version1s[i]);
            }
                        
            if(fromVersion2 < fromVersion1){
                return 1;
            }
            
            if(fromVersion2 > fromVersion1){
                return -1;
            }
        }
        return 0;
    }
```
