ABSP1

Abs(a-b) I

Link to the question: ABSP1 

HINT :

You must have already noticed that the number are in sorted order. If you do some rough work for input of 5-6 numbers and form pairs as given in the question and subtract you will notice that each element in the i-th position is added i-th times and subtracted n-1-i th times. Using this you can write your code.

SOURCE CODE :

/* ABSP1 */

/* Sushant Gupta */




#include<stdio.h>

int main()

{

    int t;

    scanf("%d",&t);

    while(t--)

    {

        int n,i;

        scanf("%d",&n);

        long long int a[n],s=0;

        for(i=0;i<n;i++)

            scanf("%lld",&a[i]);

        for(i=n-1;i>=0;i--)

            s= s+ (i*a[i]) - a[i]*(n-1-i);

        printf("%lld\n",s);



    }

    return 0;

}