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Reverse squared sum
Easy Accuracy: 84.42% Submissions: 279 Points: 2

Reena had been given an array arr[] of positive integers of size N.Help her to find the value A.

A = arr[n]*arr[n] - arr[n-1]*arr[n-1] + arr[n-2]*arr[n-2] - ......... upto index 1

Input:
1. The first line of the input contains a single integer T denoting the number of test cases. The description of T test cases follows.
2. The first line of each test case contains a single integer N.
3. The second line contains
N space-separated positive integers represents array arr.

Output: For each test case, print the value of A in a single line

Constraints:
1. 1 <= T <= 10

2. 1 <= N <= 100000
3. 1 <= arr[i] <= 100


Example:
Input:

2
3
1 2 3

4
4 8 1 2

Output:
6
51

Explanation:
Test case 1 : 3*3 - 2*2 + 1*1 = 6

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Reverse squared sum

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