How to Convert a Map of Set of Pairs in C++?

In C++, a map can be converted to a set of pairs. This can be useful when you want to create a set of pairs from a map, where each pair contains a key and a value. In this article, we will learn how to convert a map to a set of pairs in C++.

Example

Input: 
myMap = {{1, “one”}, {2, “two”}, {3, “three”}};

Output:  
Set of Pairs is : {(1, “one”), (2, “two”), (3, “three”)}

Convert Map into Set of Pairs in C++

To convert a std::map to a std::set of std::pair, we can use the range constructor of std::set that takes two iterators, one pointing to the beginning and the other to the end of the map.

C++ Program to Convert Map into Set of Pairs in C++

The below example demonstrates the use of the range constructor to convert a map to a set of pairs in C++ STL.

C++

// C++ program to show how to convert a map to a set of
// pairs

#include <iostream>
#include <map>
#include <set>
using namespace std;

int main()
{
    // Creating a map
    map<int, string> myMap
        = { { 1, "one" }, { 2, "two" }, { 3, "three" } };

    // Converting the map to a set of pairs
    set<pair<int, string> > mySet(myMap.begin(),
                                  myMap.end());

    // Printing the set of pairs
    for (auto& pair : mySet) {
        cout << "(" << pair.first << ", " << pair.second
             << ")" << endl;
    }

    return 0;
}

Output

(1, one)
(2, two)
(3, three)

Time Complexity: O(N log N), where N is the size of the map.
Auxiliary Space: O(N)