Learning set, unordered_set, and priority_queue in C++

Source: Dev.to

set

Overview

• Unique + Sorted data
• Stores unique elements
• Maintains sorted order
• Implemented using a self‑balancing BST (Red‑Black Tree)

Example

std::set

#include 
#include 

int main() {
    std::set s = {3, 1, 2, 2};
    for (int x : s) std::cout 
}

std::unordered_set

#include 

int main() {
    std::unordered_set us = {3, 1, 2, 2};
    for (int x : us) std::cout 
}

std::priority_queue (max‑heap)

int main() {
    std::priority_queue pq;
    pq.push(3);
    pq.push(1);
    pq.push(5);
    std::cout 
}

Min‑heap with std::greater

#include 
#include 

std::priority_queue, std::greater> minHeap;

Complexity

• Push / Pop: O(log n)
• Top: O(1)
• Space: O(n)

When to use

• Need k‑th largest / smallest element
• Repeated max/min extraction
• Scheduling & greedy problems