C++ Check if the Array Contains any Duplicates

Hello Everyone!

In this tutorial, we will learn how to check if the given Array contains any duplicate or not, in the C++ programming language.

This is achieved by first sorting the Array using the system defined sort() method, demonstrated below.

For better understanding, refer to the well-commented C++ code given below.

Code:

#include <iostream>
#include <bits/stdc++.h>
using namespace std;
//Program to return true if duplicate is found
bool containsDuplicate(int n[], int m)
{
 //flag to indicate the presence of duplicate
 int f = 0;
 //Sorting the array to check for duplicates
 sort(n, n + m);
 for (int i = 0; i < m - 1; i++)
 {
 if (n[i] == n[i + 1])
 {
 //if duplicate is found then set the flag to 1 and exit the loop
 f = 1;
 break;
 }
 }
 if (f == 1)
 return true;
 else
 return false;
}
int main()
{
 cout << "\n\nWelcome to Studytonight :-)\n\n\n";
 cout << " ===== Program to check if any duplicates are present in the input array ===== \n\n";
 int i, n1, n2;
 int a1[] = {2, 3, 1, 4, 5, 2, 8, 9};
 int a2[] = {2, 3, 1, 4, 5, 10, 8, 9};
 bool duplicate1 = false;
 bool duplicate2 = false;
 n1 = sizeof(a1) / sizeof(a1[0]);
 n2 = sizeof(a2) / sizeof(a2[0]);
 cout << "\n\nThe elements of the first input array are :\n\n";
 for (i = 0; i < n1; i++)
 {
 cout << a1[i] << " ";
 }
 duplicate1 = containsDuplicate(a1, n1);
 if (duplicate1)
 cout << "\n\nThe first input array contains duplicate";
 else
 cout << "\n\nThe first input array does not contain any duplicate";
 cout << "\n\n\n\nThe elements of the second input array are :\n\n";
 for (i = 0; i < n2; i++)
 {
 cout << a2[i] << " ";
 }
 duplicate2 = containsDuplicate(a2, n2);
 if (duplicate2)
 cout << "\n\nThe second input array contains duplicate";
 else
 cout << "\n\nThe second input array does not contain any duplicate";
 cout << "\n\n\n";
 return 0;
}

Output:

C++ duplicate check

We hope that this post helped you develop a better understanding of the concept of determining if the Array contains any duplicates and its implementation in C++. For any query, feel free to reach out to us via the comments section down below.

Keep Learning : )