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How to Merge Two Sorted Vector in C++?

Last Updated : 23 Jul, 2025
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Merging two sorted vectors means storing the elements of a vector into a single vector in a sorted order. In this article, we will learn how to merge two sorted vectors in C++.

The simplest way to merge the two sorted vectors is by using the merge() function.  Let’s take a look at an example:

C++ 
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 3, 5};
    vector<int> v2 = {2, 4, 6};

    // Creating a vector to store merged vector
    vector<int> v(v1.size() + v2.size());

    // Merging the two vectors
    merge(v1.begin(), v1.end(), v2.begin(),
          v2.end(), v.begin());

    for (auto i : v)
        cout << i << " ";
    return 0;
}

Output
1 2 3 4 5 6

Explanation: The merge() function merge the two vectors v1 and v2 in sorted manner and store it in the resultant vector v.

There are also some other methods in C++ to merge the two sorted vector. Some of them are as follows:

By Sorting After Concatenation

Copy both the vectors into resultant vector using vector insert() method. After that, sort the resultant using sort() to arrange the elements in sorted order.

C++ 
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 3, 5};
    vector<int> v2 = {2, 4, 6};

    // Creating a vector to store the merged vector
    vector<int> v;

    // Insert v1 and v2 into vector v
    v.insert(v.end(), v1.begin(), v1.end());
    v.insert(v.end(), v2.begin(), v2.end());

    // Sort the vector v
    sort(v.begin(), v.end());

    for (auto i : v)
        cout << i << " ";
    return 0;
}

Output
1 2 3 4 5 6

Using Multiset

A multiset stores its elements in a sorted order by default. It can be used as a temporary storage medium to combine the elements of both vectors while maintaining sorted order, and then transfer all the elements into the resultant vector.

C++ 
#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> v1 = {1, 3, 5};
    vector<int> v2 = {2, 4, 6};

    // Insert elements of v1 and v2 into multiset
    multiset<int> ms(v1.begin(), v1.end());
    ms.insert(v2.begin(), v2.end());

    // Copying elements of multiset into vector v
    vector<int> v(ms.begin(), ms.end());

    for (auto i : v)
        cout << i << " ";
    return 0;
}

Output
1 2 3 4 5 6

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