Write a C program to find the duplicate element in an array?

Find the duplicate number in array: For example, an array with length 5 contains numbers {1, 2, 3, 4, 4}, the duplicated number is 4. Suppose that the duplicated number in the array is m in given example. The sum of all numbers in the array, denoted as arrSum, should be the result of 1+2+...+(n-1)+m. It is not difficult to get the sum of 1+2+...+(n-1), which is denoted as sum. The duplicated number m will be the difference of arrSum and sum. Following C program demonstrates how do we detect a repeated element in an integer array?.

/* An array of size N contains numbers ranging from 1 to N-1.
   There is exactly one number is duplicated in the array.
   Write a C program to find the duplicated number?
*/
#include <stdio.h>
#define N 5
int main()
{
  int arr[N]; //contains integers from 1 to N-1
  int arrSum = 0; //sum of array elements
  int sum = (N * (N - 1)) / 2; //sum of 1 to N-1
  int i; //loop counter
  printf("Enter %d integers form 1 to %d, with one duplicate:", N, N-1);
  for (i = 0; i < N; i++)
  {
    scanf ("%d", &arr[i]);
    arrSum += arr[i];
  }
 
  printf("\nDuplicate number is: %d\n", arrSum - sum);
}



Get Free Tutorials by Email

About the Author

is the main author for cs-fundamentals.com. He is a software professional (post graduated from BITS-Pilani) and loves writing technical articles on programming and data structures.

Today's Tech News

UK regulator has 'huge concerns' over Uber breachPosted on Wednesday November 22, 2017

A data breach affecting 57 million customers and drivers should not have been concealed, the information commissioner says.

Android phones 'betray' user location to GooglePosted on Wednesday November 22, 2017

The devices send location data back to Google even when location services are switched off.

Budget 2017: Funding for AI, 5G and digital skillsPosted on Wednesday November 22, 2017

The chancellor acknowledged the digital revolution would change the way people lived and worked.

Courtesy BBC News

AD BLOCKER DETECTED!

Advertisements help running this site for free.


To view the content please disable AdBlocker and refresh the page.

×