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.

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.

Related Topics:
String

// OJ: https://leetcode.com/problems/compare-version-numbers/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(N)
class Solution {
public:
    int compareVersion(string a, string b) {
        istringstream sa(a), sb(b);
        while (sa.good() || sb.good()) {
            string x, y;
            getline(sa, x, '.');
            getline(sb, y, '.');
            int v1 = x.size() ? stoi(x) : 0, v2 = y.size() ? stoi(y) : 0;
            if (v1 > v2) return 1;
            else if (v1 < v2) return -1;
        }
        return 0;
    }
};

Or

// OJ: https://leetcode.com/problems/compare-version-numbers/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(1)
class Solution {
public:
    int compareVersion(string a, string b) {
        istringstream sa(a), sb(b);
        while (sa.good() || sb.good()) {
            int v1 = 0, v2 = 0;
            sa >> v1;
            sb >> v2;
            if (v1 > v2) return 1;
            else if (v1 < v2) return -1;
            if (sa.good()) sa.get();
            if (sb.good()) sb.get();
        }
        return 0;
    }
};