### BERNARB.01's blog

By BERNARB.01, 13 days ago,

Hello, I was solving the problem 461B - Appleman and Tree but misread the problem statement — thinking that I have to calculate the number of ways such that each subtree has at least one black node, but I couldn't find a solution to this. Can anyone help me with this version of the problem?

• +18

By BERNARB.01, history, 15 months ago,

### Hello codeforces,

On this problem 1277E - Две ярмарки, there is t test cases and I am using a vector<vector> ed(N) to store the edges of the graph, so in end of each test case I need to clear my vector ed so I created another one vector<vector> em(N) and it's empty all the running time, in the end of each test case I did ed = em to save time, but I were always getting a TLE on the 2nd test, and I don't know why. In the first submission 68468115, I did

vector<vector<int> > ed(N), em(N);
int main() {
cin >> t;
while(t--){
...
...
...
ed = em;
}
return 0;
}


But when I did the following in this submission 68489443, I got an AC.

vector<vector<int> > ed(N);
int main() {
cin >> t;
while(t--){
...
...
...
for(int i=0; i<n; i++) ed[i].clear();
}
return 0;
}


Can someone explain why I were getting a TLE on the first submission, even that in the first submission I were doing one operation but in the second one I were doing N operations.