Find the first repeated element in an array

Posted on Apr 24, 2020

C program to find the first repeated element in an array.

Program

#include<stdio.h>
#include<conio.h>
#define MAX 50

void read_array(int a[MAX], int n)
{
    int i;
    for(i=0;i<n;i++)
    {
        printf("Element %d\t:",i+1);
        scanf("%d",&a[i]);
    }
}

void first_rep(int a[MAX], int n)
{
    int i, j, num, flag = 0;
    for(i=0;i<n;i++)
    {
        for(j=i+1;j<n;j++)
        {
            if(a[i] == a[j])
            {
                num = a[i];
                flag = 1;
                break;
            }
        }
        if(flag == 1)
            break;
    }

    if(flag == 0)
        printf("\nThere is no repeating element");
    else
        printf("\nFirst repeated element is %d",num);
}

void main()
{
	int arr[MAX];
    int i, n;

    printf("Enter the number of elements in the array\t:");
    scanf("%d",&n);

    printf("Enter the elements of the array\n");
    read_array(arr, n);

    first_rep(arr, n);

    getch();
}

Output

********** Run1 ********** 

Enter the number of elements in the array       :5
Enter the elements of the array
Element 1       :1
Element 2       :2
Element 3       :3
Element 4       :4
Element 5       :5

There is no repeating element


********** Run2 ********** 

Enter the number of elements in the array       :5
Enter the elements of the array
Element 1       :1
Element 2       :2
Element 3       :3
Element 4       :2
Element 5       :1

First repeated element is 1