C#: Count a total number of duplicate elements in an array

Last update on December 20 2024 12:36:50 (UTC/GMT +8 hours)

Write a C# Sharp program in to count duplicate elements in an array.

Sample Solution:-

C# Sharp Code:

using System;  // Importing necessary namespace

public class Exercise5  // Declaration of the Exercise5 class
{  
    public static void Main()  // Main method, entry point of the program
    {
        int[] arr1 = new int[100];  // Declaration of an integer array 'arr1' with size 100
        int[] arr2 = new int[100];  // Declaration of another integer array 'arr2' with size 100
        int[] arr3 = new int[100];  // Declaration of another integer array 'arr3' with size 100
        int s1, mm = 1, ctr = 0;  // Declaration of variables 's1', 'mm', and 'ctr'
        int i, j;  // Declaration of loop control variables 'i' and 'j'

        // Display a message to count the total number of duplicate elements in an array
        Console.Write("\n\nCount total number of duplicate elements in an array:\n");
        Console.Write("---------------------------------------------------------\n");

        Console.Write("Input the number of elements to be stored in the array :");
        s1 = Convert.ToInt32(Console.ReadLine());  // Read the number of elements from the user and store it in 's1'

        Console.Write("Input {0} elements in the array:\n", s1);  // Prompt the user to input 's1' elements
        for (i = 0; i < s1; i++)
        {
            Console.Write("element - {0} : ", i);
            arr1[i] = Convert.ToInt32(Console.ReadLine());  // Read user input and store it in the array 'arr1'
        }

        // Copy elements from 'arr1' to 'arr2' and initialize 'arr3' with 0
        for (i = 0; i < s1; i++)
        {
            arr2[i] = arr1[i];  // Copy each element from 'arr1' to 'arr2'
            arr3[i] = 0;  // Initialize 'arr3' with 0
        }

        // Mark the elements that are duplicate in 'arr3'
        for (i = 0; i < s1; i++)
        {
            for (j = 0; j < s1; j++)
            {
                if (arr1[i] == arr2[j])
                {
                    arr3[j] = mm;  // Mark duplicate elements in 'arr3' with 'mm'
                    mm++;  // Increment 'mm'
                }
            }
            mm = 1;  // Reset 'mm' to 1
        }

        // Count the number of duplicate elements in 'arr3'
        for (i = 0; i < s1; i++)
        {
            if (arr3[i] == 2)
            {
                ctr++;  // Increment 'ctr' for each duplicate element found in 'arr3'
            }
        }

        Console.Write("The number of duplicate elements is: {0} \n", ctr);  // Output the count of duplicate elements
        Console.Write("\n\n");  // Extra newline for formatting
    }
}

Sample Output:

                                                                                                       
Count total number of duplicate elements in an array:                                                         
---------------------------------------------------------                                                     
Input the number of elements to be stored in the array :3                                                     
Input 3 elements in the array :                                                                               
element - 0 : 2                                                                                               
element - 1 : 2                                                                                               
element - 2 : 4                                                                                               
Total number of duplicate elements found in the array is : 1 

Flowchart:

C# Sharp Code Editor:

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