23_Compare_Version_Numbers.cpp

// 165. Compare Version Numbers

// Given two version strings, version1 and version2, compare them. A version string consists of revisions separated by dots '.'. The value of the revision is its integer conversion ignoring leading zeros.

// To compare version strings, compare their revision values in left-to-right order. If one of the version strings has fewer revisions, treat the missing revision values as 0.

// Return the following:

// If version1 < version2, return -1.
// If version1 > version2, return 1.
// Otherwise, return 0.
 

// Example 1:

// Input: version1 = "1.2", version2 = "1.10"

// Output: -1

// Explanation:

// version1's second revision is "2" and version2's second revision is "10": 2 < 10, so version1 < version2.

// Example 2:

// Input: version1 = "1.01", version2 = "1.001"

// Output: 0

// Explanation:

// Ignoring leading zeroes, both "01" and "001" represent the same integer "1".

// Example 3:

// Input: version1 = "1.0", version2 = "1.0.0.0"

// Output: 0

// Explanation:

// version1 has less revisions, which means every missing revision are treated as "0".

 

// Constraints:

// 1 <= version1.length, version2.length <= 500
// version1 and version2 only contain digits and '.'.
// version1 and version2 are valid version numbers.
// All the given revisions in version1 and version2 can be stored in a 32-bit integer.

class Solution
{
public:
    int compareVersion(string version1, string version2)
    {
        stringstream s1(version1), s2(version2);
        string token1, token2;

        while (getline(s1, token1, '.') || getline(s2, token2, '.'))
        {
            int num1 = token1.empty() ? 0 : stoi(token1);
            int num2 = token2.empty() ? 0 : stoi(token2);
            if (num1 < num2)
                return -1;
            if (num1 > num2)
                return 1;
            token1.clear();
            token2.clear();
        }
        return 0;
    }
};