# 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.

Here is an example of version numbers ordering:

0.1 < 1.1 < 1.2 < 13.

## Code

``````public class Solution {
public int compareVersion(String version1, String version2) {
long a = 0, b =0;
int v1len = version1.length(), v2len = version2.length();
int i = 0, j = 0;
while (i < v1len || j < v2len) {
a = 0; b =0;
while (i < v1len && version1.charAt(i) != '.') {
a = a * 10 + version1.charAt(i) - '0';
++i;
}
++i;
while (j < v2len && version2.charAt(j) != '.') {
b = b * 10 + version2.charAt(j) - '0';
++j;
}
++j;
if (a > b) return 1;
if (a < b) return -1;
}
return 0;
}
}
``````