Compare Version Numbers

Desicription

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.

Example 1:

1
2
Input: version1 = "0.1", version2 = "1.1"
Output: -1

Example 2:

1
2
Input: version1 = "1.0.1", version2 = "1"
Output: 1

Example 3:

1
2
Input: version1 = "7.5.2.4", version2 = "7.5.3"
Output: -1

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
class Solution {
public:
    int compareVersion(string version1, string version2) {
        int num1 = 0;
        int num2 = 0;
        int n1 = version1.size();
        int n2 = version2.size();
        int i = 0;
        int j = 0;
        while(i < n1 || j < n2) {
            while(i < n1 && version1[i] != '.')
                num1 = num1 * 10 + version1[i++] - '0';
            while(j < n2 && version2[j] != '.')
                num2 = num2 * 10 + version2[j++] - '0';    
            if(num1 > num2)
                return 1;
            else if(num1 < num2)
                return -1;
            num1 = 0;
            num2= 0;
            i++;
            j++;
        }
        return 0;
    }
};