Could someone explain the meaning of vector()

Question

I'm solving the Clone Graph in Leetcode, but I encountered a problem inside the following codes

 class Node {
public:
    int val;
    vector<Node*> neighbors;
    Node() {
        val = 0;
        neighbors = vector<Node*>();
    }
    Node(int _val) {
        val = _val;
        neighbors = vector<Node*>();
    }
    Node(int _val, vector<Node*> _neighbors) {
        val = _val;
        neighbors = _neighbors;
    }
};

what does it mean by the statement neighbors = vector<Node*>();. More specifically, vector<Node*>(). Why is it followed by parentheses?

You should probably learn about [objects](https://www.w3schools.com/cpp/cpp_classes.asp), [pointers](https://www.w3schools.com/cpp/cpp_pointers.asp) and [vectors](https://www.geeksforgeeks.org/vector-in-cpp-stl/) — Marko Borković, Aug 11 '21 at 10:51
Sites such as LeetCode assume you know the computer language you will be using to solve the problem. If you are asking basic questions about C++ such as this, maybe you chose the wrong language to try and solve the LeetCode problem. LeetCode and other such sites are not in the business of teaching you C++. — PaulMcKenzie, Aug 11 '21 at 10:51
Get your favorite book about `c++` and look up constructors. — Mestkon, Aug 11 '21 at 10:52
It doesn't do anything here because `neighbors` was already initialized with its default constructor. — interjay, Aug 11 '21 at 10:53

Vlad from Moscow · Accepted Answer · 2021-08-11T11:34:07.743

Actually this statement in the constructors of the class Node

neighbors = vector<Node*>();

is redundant.

There is used the move assignment operator that assigns an empty vector created by calling the default constructor vector<Node*>() of the class std::vector<Node *> to the already created empty vector neighbors that is a data member of the class Node.

You may remove this statement from the constructors of the class Node. In fact it has no effect.

Could someone explain the meaning of vector()

1 Answers1