c++ - 将类型对列表的 vector 大小设置为用户在类中给定的大小

Question

刚接触 C++ 中的图形 STL 很抱歉，如果它是初学者级别的问题。请告诉我如何设置列表 vector 的大小

#include <bits/stdc++.h>

#include <iostream>
using namespace std;
class my_graph {
 public:
  int vertices;
  list<pair<int, int>> *adjacency_list;
  vector<list<pair<int, int>>> adjacencyList;

  my_graph(int ver) {
    this->vertices = ver;
    adjacency_list = new list<pair<int, int>>[vertices];

    // what should i type here to make the size of
    // vector type adjacencyList
    // to user defined size in this constructor.
    // just like i did for list type adjacency_list
  }
};

Answer 1

您可以使用 resize() 方法。

class my_graph {
public:

    int vertices;
    list<pair<int, int>> *adjacency_list;
    vector< list< pair<int, int> > > adjacencyList;

    my_graph(int ver) {
        this->vertices = ver;
        adjacency_list = new list<pair<int, int>>[vertices];
        adjacencyList.resize(vertices);
    }
};