How to Access Elements of Set of Maps in C++?

In C++, a set of maps can be used to store multiple maps of key-value pairs sorted according to their number and values of elements such as graphs. In this article, we will explore how we can access the elements of a set of maps in C++.

Example:

Input: { { {1: "C++"}, {2:" Python"} },
              { {3:" Java"}, {4: "Rust"} }
            }

Output:
Value Associated with Key 3: Rust

Access Elements of Set of Maps in C++

The Set of Map is a multidimensional container, so there will be multilevel access in the set of maps. Assume that you want to access the element with key ‘k’:

• We will first use the range-based for loop to iterate through the parent set.
• Now, inside the first loop, each element will be a map container. So, we will find the value of ‘k’ using the std:map::at() function.

C++ Program to Access Elements of Set of Pairs

C++

// C++ Program to Check for a Specific Key in a Set of Maps

#include <iostream>
#include <map>
#include <set>

using namespace std;

int main()
{
    // Define a set of maps
    set<map<int, char> > setOfMaps;

    // Define some maps
    map<int, char> map1{ { 1, 'a' },
                         { 3, 'b' },
                         { 5, 'c' } };
    map<int, char> map2{ { 1, 'f' },
                         { 3, 'e' },
                         { 5, 'd' } };

    // Add the maps to the set
    setOfMaps.insert(map1);
    setOfMaps.insert(map2);

    // The key you are interested in
    int key = 3;

    // Iterate over the set of maps
    for (const auto& map : setOfMaps) {
        // Check if the key exists in the map
        if (map.count(key) > 0) {
            // Access the value associated with the key
            char value = map.at(key);
            cout << "Value associated with key " << key
                 << " is " << value << endl;
        }
    }

    return 0;
}

Output

Value associated with key 3 is b
Value associated with key 3 is e

Time Complexity: O(N x M) where N is the size of the Set and M is the size of Maps present inside the set.
Auxilary Space: O(1)