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.

Solution

依照题意对比即可

Complexity

时间复杂度 O(n),空间复杂度 O(1)

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;
    }
}