# 165. Compare Version Numbers

Difficulty: Easy

Frequency: N/A

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 < 13.37`

My solution:
Data structure:
string
Steps:
Complexity:
Runtime: O(n)
Space: O(1)
Test cases:
Corner cases:
1. “1”, “1.1”
2. “1.0.1”, “1”
3. “01”, “1”
Code:
```class Solution {
public:
int compareVersion(string version1, string version2) {
for (; version1 != version2; version1 = get_substring(version1), version2 = get_substring(version2)) {
if (stoi(version1) != stoi(version2)) return stoi(version1) > stoi(version2) ? 1 : -1;
}
return 0;
}

string get_substring(string v) {
for (int i = 0; i < v.size(); i++) {
if (v[i] == '.') return v.substr(i + 1);
}
return "0";
}
};
```

Another solution:
Data structure:
steps:
Complexity:
Runtime:
Space:
Code:

Things to learn:

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