How to Merge Multiple Vectors into a List in C++?

In C++, a list is a not contiguous data storage container that implements the linked lists and a vector is a contiguous data storage container that implements dynamic arrays that can resize according to the need. In this article, we will learn how to merge multiple vectors into a single list in C++.

Input:
vector<int> vec1 = {1, 2, 3};
vector<int> vec2 = {4, 5, 6};
vector<int> vec3 = {7, 8, 9};

Output:
Elements in a list after merging: 1 2 3 4 5 6 7 8 9

Merge Multiple Vectors into a List in C++

To merge multiple vectors into a single list, we can use std::map::insert() which allows us to insert the range of elements in the list. It is the member function of the std::list container that takes the iterator to the beginning and the iterator to the end of the range and inserts all the elements in that range into its list.

C++ Program to Merge Multiple Vectors into a Single List

C++

// C++ Program to merge multiple vectors into a single list
#include <iostream>
#include <list>
#include <vector>
using namespace std;
int main()
{
    // creating vector to be merge into single list
    vector<int> vec1 = { 1, 2, 3 };
    vector<int> vec2 = { 4, 5, 6 };
    vector<int> vec3 = { 7, 8 };

    // creating a list by merging vectors using insert()
    list<int> myList;
    myList.insert(myList.end(), vec1.begin(), vec1.end());
    myList.insert(myList.end(), vec2.begin(), vec2.end());
    myList.insert(myList.end(), vec3.begin(), vec3.end());

    // Printing the list
    cout << "Elements in Merged List: " << endl;
    for (auto i : myList)
        cout << i << " ";
    cout << endl;
    return 0;
}

Output

Elements in Merged List: 
1 2 3 4 5 6 7 8 

Time Complexity: O(N)
Auxiliary Space: O(N)

We can also use std::copy() with back_inserter() to merge multiple vectors into a single list in C++.