Set of Maps in C++

In C++, Sets are containers that allow the users to store unique elements in sorted order while maps containers store key-value pairs in sorted order based on the keys. In this article, we will discuss how to combine these two containers and create a Set of Maps in C++.

Example

Input:
MySetOfMaps = { { {1, "C++"}, {2, "Java"}, {3, "Python"} },
                                 { {4, "DSA"}, {5, "OS"}, {6, "DBMS"} } }

Output:
Set Elements:
Map:0 { (1, C++) (2, Java) (3, Python) }
Map:1 { (4, DSA) (5, OS) (6, DBMS) }

Set of Maps in C++ STL

In C++, a set of maps can be created by nesting a std::map container inside the std::set container. We can do this by specifying the elements of the set to be a map in the set declaration.

C++ Program to Create a Set of Maps

C++

// C++ Program to Create a Set of Maps
#include <iostream>
#include <map>
#include <set>

using namespace std;

int main()
{
    // Create a set of maps
    set<map<int, string> > MySet;

    // Create maps to insert into the set
    map<int, string> map1
        = { { 1, "C++" }, { 2, "Java" }, { 3, "Python" } };
    map<int, string> map2
        = { { 4, "DSA" }, { 5, "OS" }, { 6, "DBMS" } };

    // Insert the maps into the set
    MySet.insert(map1);
    MySet.insert(map2);

    // Print the set of maps
    cout << "Set Elements: " << endl;
    int i = 0;
    for (auto& map : MySet) {
        cout << "Map " << i << ": {";

        for (auto& pair : map) {
            cout << " (" << pair.first << ", "
                 << pair.second << ")";
        }

        cout << " }" << endl;
        i++;
    }

    return 0;
}

Output

Set Elements: 
Map 0: { (1, C++) (2, Java) (3, Python) }
Map 1: { (4, DSA) (5, OS) (6, DBMS) }

Time Complexity: O(N * M) to traverse N maps present in the set where M is the average number of elements in each map.
Auxilary Space : O(1)