Find Duplicate in Range 0 and n-1

Code

#include <stdio.h>

bool  check( int arr[], int pos )
{
    for(int i=0;i< pos;i++)
    {
        if(arr[i] ==arr[pos] )
        {
            return  false;
        }
    }
    return true;
}
int find_duplicate(int arr[], int n) {
    // Your logic here
    for(int i=0 ;i<n;i++)
    {
        int pos =i;
        if(check(arr,pos) == false)
        {
            return arr[pos];
        }
    }
    return -1;
}

int main() {
    int n;
    scanf("%d", &n);

    int arr[100];
    for (int i = 0; i < n; i++) scanf("%d", &arr[i]);

    int result = find_duplicate(arr, n);
    printf("%d", result);
    return 0;
}

Solving Approach