Introduction

Set is a data structure that only stores unique elements.

Types of Set

There are two types of set in cpp.

1. Ordered Set - Maintain sorting while insertion
2. Unordered Set - Insert in random order which makes it fast.

Initialize

#include <set>
using namespace std;
int main(){
    set<int> iSet;
    unordered_set<int> uSet;
    iSet.insert(10);
    uSet.insert(10);
}

Check for an element

if (iSet.find(20) != iSet.end()) {
    cout << "20 is in the set" << endl;
}
if (uSet.find(20) != uSet.end()) {
    cout << "20 is in the set" << endl;
}

Erase an element

iSet.erase(20);
uSet.erase(20);

Iterate over an element

Iteration is same in ordered and Unordered Set

for (auto it = iSet.begin(); it != iSet.end(); ++it) {
    std::cout << *it << " ";
}

Get the size

std::cout << "Size: " << iSet.size() << std::endl;
std::cout << "Unordered Size: " << uSet.size() << std::endl;

Clear the set

iSet.clear();

Difference Between Ordered and Unordered set

Application

1. Removing duplicates in an array
2. Set Operations