From few days I am having trouble to get access to CF using cellular data hotspot from mobile to my PC. But i can get access using wifi. If i use VPN on my pc with cellular data hotspot then only i can enter in CF. Why is that? Anyone faced similar issues?

i was writing this code and faced this unknown behavior.

void solve(){
    string s = "a";
    for(int i = 0; i < s.size() - 1; i++){
        cout << "1st for loop\n";
        if(s[i] == s[i + 1]){
            cout << s[i] << s[i + 1] << '\n';
            return;
        }
    }
    for(int i = 0; i < s.size() - 2; i++){
        cout << "2nd for loop " << i << '\n';
        if(s[i] != s[i + 1] and s[i] != s[i + 2] and s[i + 1] != s[i + 2]){
            cout << s[i] << s[i + 1] << s[i + 2] << '\n';
            return; 
        }
    }
    cout << -1;
}

shouldn't it print -1? then why it enters into second for loop as the size of my string is 1? Can anyone help me to understand this behavior?

can anyone help me to find two node that are not adjacent to each other but has highest degree.

suppose node 1 with 4 degree, node 5 with 4 degree but node 1 and 5 are adjacent so we cant choose node 1 and 5. another node 8 has a degree of 3. and all other node has degree <= 3. also node 5 and 8 are not adjacent, so we can choose node 1 and 8, or 5 and 8. I did not come up with any idea so seeking for help