# 165. Compare-Version-Numbers

difficulty: Medium

&#x20;section pre{ background-color: #eee; border: 1px solid #ddd; padding:10px; border-radius: 5px; }&#x20;

Compare two version numbers *version1* and *version2*.\
&#x20;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.

## Method One

```java
class Solution {
    public int compareVersion(String version1, String version2) {
        String[] v1 = version1.split("\\.");
        String[] v2 = version2.split("\\.");

        int size1 = v1.length;
        int size2 = v2.length;
        int maxSize = Math.max(size1, size2);

        for(int i = 0; i < maxSize; i++) {
            int i1 = i < size1 ? Integer.parseInt(v1[i]) : 0;
            int i2 = i < size2 ? Integer.parseInt(v2[i]) : 0;
            if( i1 != i2 ) {
                return i1 > i2 ? 1 : -1;
            } 
        }
        return 0;
    }

​
}
​
```

又一种写法

```java
class Solution {
    public int compareVersion(String version1, String version2) {
        String[] v1 = version1.split("\\.");
        String[] v2 = version2.split("\\.");
        int p = 0;
        while( p < v1.length || p < v2.length ) {
            int curV1 = p <  v1.length ? Integer.parseInt( v1[p]) : 0;
            int curV2 = p <  v2.length ? Integer.parseInt( v2[p]) : 0;
            if(curV1 < curV2) {
                return -1;
            }
            if(curV1 > curV2) {
                return 1;
            }
            p++;
        }
        return 0;
    }
}
```
