Find duplicate element using Sorting approach

duplicate_sorting.cpp

#include <bits/stdc++.h>
using namespace std;

int sorting_duplicate(int arr[], int n)
{
    //Sort the array using STL sort function or write own sorting algorithm(merge sort or heap sort)
    sort(arr, arr + n);
    for (int i = 1; i < n; i++)
    {
        //As the list is sorted,if two consecutive values are found, return the value as it is duplicate 
        if (arr[i] == arr[i + 1])
            return arr[i];
    }
    // If duplicate value is not found, return -1
    return -1;
}

// Driver Code
int main()
{
    //Create an array with 1 duplicate value
    int arr[7] = {1, 2, 3, 9, 3, 6, 5};
    
    //Calculate size of array
    int n = sizeof(arr) / sizeof(arr[0]);
    
    //Find out either the duplicate element present in the array or -1
    int duplicate = sorting duplicate(arr, n);

    //Print duplicate array element
    cout << duplicate << endl;
    return 0;
}