How to find Duplicate elements in an array in C

 #include<stdio.h>

int main()

{

int n,i,j,flag=0,arr[20];

printf("Enter size of array : \n");

scanf("%d",&n);

printf("array element are =\n");

for(i=0;i<n;i++)

{

printf("\n arr[%d]= ",i);

scanf("%d",&arr[i]);

}

for(i=0;i<n;i++)

{

for(j=i+1;j<n;j++)

{

if(arr[i]==arr[j]&&i!=j)

{

flag=1;

printf("Duplicate number position are %d and %d",i,j);

}

}

}

if(flag==0)

printf("no duplicate");

}

Output:

Enter size of array :

5

array element are =

 arr[0]= 2

 arr[1]= 3

 arr[2]= 4

 arr[3]= 3

 arr[4]= 6

Duplicate number position are 1 and 3