165. Compare Version Numbers

class Solution {
public:
    int compareVersion(string version1, string version2) {

        int i=0, j=0, l1=version1.length(), l2=version2.length();
        int num1 = 0, num2 = 0;

        while(i<l1 || j<l2)
        {
            while(i<l1 && version1[i]!='.')
            {
                num1 = num1 * 10 + (version1[i] - '0');
                i++;
            }

            while(j<l2 && version2[j]!='.')
            {
                num2 = num2 * 10 + (version2[j] - '0');
                j++;
            }


            if(num1 < num2)
                return -1;
            else if(num1 > num2)
                return 1;

            i++;
            j++;

            num1 = 0;
            num2 = 0;
        }

        return 0; 
    }
};