CompareVersionNumbers.java

// O(n) , where n => no of elements in the version part
// O(1), space complexity
class CompareVersionNumbers {

    public int compareVersion(String version1, String version2) {
        String[] version1List = version1.split("\\."); // Note your cant directly use split(".") because if will treat he regex as any character
        String[] version2List = version2.split("\\.");

        int s1 = 0;
        int s2 = 0;

        int len1 = version1List.length;

        int len2 = version2List.length;

        while(s1<len1 && s2<len2){
            int val1 = Integer.parseInt(version1List[s1]);
            int val2 = Integer.parseInt(version2List[s2]);
            s1++;
            s2++;

            if(val1>val2){
                return 1;
            } else if(val1<val2){
                return -1;
            } else{
                // continue
            }

        }

        while(s1<len1){
            int val1 = Integer.parseInt(version1List[s1]);
            s1++;
            if(val1>0){
                return 1;
            }
        }


        while(s2<len2){
            int val2 = Integer.parseInt(version2List[s2]);
            s2++;
            if(val2>0){
                return -1;
            }
        }

        return 0;
    }
}