Most efficient way to clear array of vectors

Question

I have a graph representation which looks like this

vector<int> Graph[MAXN]

Next, I want to remove all previously set vectors. What is the fastest way to do it ?

Answer 1

There's no real question of "efficiency" here. You must iterate through your array, and you must invoke std::vector<int>::clear() on each element of that array. So, just do it :

for (auto& v : Graph) {
   v.clear();
}