Recap - Unique Numbers

Part of the Logic & Flow section of Coddy's C++ journey — lesson 40 of 56.

Challenge

Easy

Create a program that reads a series of integers and uses a std::set to automatically filter out duplicates, then prints the count of unique numbers. This demonstrates the primary advantage of sets - maintaining collections of unique elements without manual duplicate checking.

The following inputs will be provided:

An integer n representing how many numbers will be entered
Then n integers to be processed

Your program should:

Create an empty std::set<int>
Read the number of integers that will be entered
Use a loop to read each integer and insert it into the set using the .insert() method
After processing all numbers, use the .size() method to get the count of unique numbers
Print the result showing how many unique numbers were found

Use the following exact output format:

Unique numbers: [count]

The set will automatically handle duplicate removal - when you try to insert a number that already exists, the set ignores the duplicate insertion. This means you don't need to manually check for duplicates; simply insert all numbers and let the set maintain uniqueness for you. The final size of the set represents exactly how many distinct numbers were in the input.

Try it yourself

#include <iostream>
#include <set>
using namespace std;

int main() {
    // Read the number of integers
    int n;
    cin >> n;
    
    // Create an empty set to store unique integers
    set<int> uniqueNumbers;
    
    // TODO: Write your code here
    // Use a loop to read n integers and insert them into the set
    
    // Output the result
    cout << "Unique numbers: " << uniqueNumbers.size() << endl;
    
    return 0;
}

All lessons in Logic & Flow

3Project: Task List Tool

Project Overview Adding a Task

Viewing Tasks

Removing a Task

Finishing the Tool

6Sets (Unique Elements)

Introducing std::set Create Set & Add Elements Checking for Elements Removing Elements Iterating Over a SetRecap - Unique Numbers

9Final Challenges

Vector Data Filtering Map Value Search Pointer and Dynamic Array