Compare Version Numbers

• Time : $O(max(|A|,|B|))$
• Space : $O(|A| + |B|)$

c++

int Solution::compareVersion(string A, string B) {
    int i = 0, j = 0;
    while(i < A.length() or j < B.length()) {
        int ni = i, nj = j;
        string AA = "", BB = "";
        while(ni < A.length() and A[ni] != '.') AA.push_back(A[ni++]);
        while(nj < B.length() and B[nj] != '.') BB.push_back(B[nj++]);
        reverse(begin(AA), end(AA));
        reverse(begin(BB), end(BB));
        while(AA.length() and AA.back() == '0') AA.pop_back();
        while(BB.length() and BB.back() == '0') BB.pop_back();
        if(AA.length() != BB.length()) return AA.length() > BB.length() ? 1 : -1;
        reverse(begin(AA), end(AA));
        reverse(begin(BB), end(BB));
        if(AA != BB) return AA > BB ? 1 : -1;
        i = ni + 1, j = nj + 1;
    }
    return 0;
}