ABSP1  abs(ab) I
Recently Mr. Kopa Samsu is learning programming. On a very renowned online judge, he found a problem:
You are given an array of N numbers in nondecreasing order. You have to answer the summation of the absolute difference of all distinct pairs in the given array.
Do you know what distinct pair means? Suppose you have an array of 3 elements: 3 5 6
Then all the distinct pairs are:
3 5
3 6
5 6
For this problem, Mr. Kopa Samsu implemented an algorithm to find the summation of the absolute difference of all distinct pairs. His algorithm was:
int ABS(int a[], int n) { int sum = 0; for (int i = 1; i <= n ;i++) { for (int j = i + 1; j <= n; j++) { sum += abs(a[i]  a[j]); } } }
After a great hard work, he finished the code. But alas!!! Frustration came around him when he submitted his code, the judge gave the verdict “TLE” (Time Limit Exit). “How can I get rid of TLE?” he thought a lot but couldn't find any way. Then suddenly, he remembered about you that you (his friend) is very good at programming. So, he came to you seeking your help. Can you help him solving this problem?
Input
The input data set starts with an integer T (T <= 1000), the number of test cases. Then every test case starts with a integer N (N <= 10000), the number of elements in the array. After that, the next line contains N integers A[i], where 1 <= i <= N and 1 <= A[i] <= 1000000000 & A[i] <= A[i+1].
Output
Every test case should output an integer “X”, where X is the summation of the absolute difference of all the distinct pair.
Example
Input: 3 3 1 2 3 3 1 4 5 3 2 4 6 Output: 4 8 8
Problem Set: S.M. Shaheen Sha, Raihat Zaman Neloy Data Set & Solution: Raihat Zamane Neloy
hide comments
shikhar_may7:
20191014 15:03:26
Observation : each a[i] is added i times and is subtracted ni1 times. :) 

sonuexpc:
20191001 16:14:25
use long long int instead of int cost me 1 WA :(


angryninja:
20190904 22:47:39
Distinct pairs don't mean different nos, it means different index. (As said by @sktibrewal) Last edit: 20190904 22:48:19 

a_l_o_n_e:
20190825 19:35:17
AC in one go!!! 

syed_tanveer:
20190417 09:10:13
AC with 0.00s :) 

sandeep48:
20190107 06:05:40
no need to declare array


deependra_18:
20190102 16:36:15
for this quesn don't trust spoj toolkit 

vipul_17:
20180916 13:12:14
AC with 0.05..:)


vengatesh15:
20180812 20:22:46
think reverse 

anirudnits:
20180720 21:19:31
don't trust spoj toolkit for this one 
Added by:  Raihat Zaman Neloy 
Date:  20140125 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 