Maximize sum of consecutive differences in a circular array

Question -

Given an array of n elements. Consider array as circular array i.e element after an is a1. The task is to find maximum sum of the difference between consecutive elements.  find |a1 – a2| + |a2 – a3| + …… + |an – 1 – an| + |an – a1|.

Example - 

Input : arr[] = { 4, 2, 1, 8 }
Output : 18
Rearrange given array as : { 1, 8, 2, 4 }
Sum of difference between consecutive element
= |1 - 8| + |8 - 2| + |2 - 4| + |4 - 1|
= 7 + 6 + 2 + 3
= 18.

Input : arr[] = { 10, 12, 15 }
Output : 10

Implementation - 

//sum=|arr[i]-arr[i+1] |+......

#include<iostream>

using namespace std;

int calculatesum(int arr[],int n)

{

    int sum=0;

    for(int i=0;i<n;i++){

        int temp=arr[i]-arr[i+1];

        if(i==n-1)

        temp=arr[n-1]-arr[0];

        if(temp<0)

            temp=-temp;

        sum+=temp;

    }

    return sum;

}

int main()

{

    int n;

    cout<<"Enter the number of the elements : ";cin>>n;

    int arr[n];

    cout<<"Enter elements : "<<endl;

    for(int i=0;i<n;i++)

        cin>>arr[i];

    int sum=calculatesum(arr,n);

    cout<<endl<<"Sum is : "<<sum<<endl;

    return 0;

}

Time complexity - O(n)

Extra space -O(1)