How does a set handle duplicate elements?

A set automatically prevents duplicate elements. When you attempt to insert a duplicate value into a set, it simply ignores the insertion and does not add the duplicate. This ensures that all elements in a set are unique. For example, in C++ using the STL set container, if you insert the same integer multiple times, only one instance of that integer will be stored in the set.

Here's a brief example in C++:

#include <iostream>
#include <set>

int main() {
    std::set<int> numbers;
    numbers.insert(10);
    numbers.insert(20);
    numbers.insert(10); // Duplicate, will not be added

    std::cout << "Set size: " << numbers.size() << std::endl; // Output will be 2
    return 0;
}

In this example, the size of the set will be 2, even though we attempted to insert the number 10 twice.