101863: [AtCoder]ABC186 D - Sum of difference
Memory Limit:256 MB
Time Limit:2 S
Judge Style:Text Compare
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Solved:0
Description
Score : $400$ points
Problem Statement
Given are $N$ integers $A_1,\ldots,A_N$.
Find the sum of $|A_i-A_j|$ over all pairs $i,j$ such that $1\leq i < j \leq N$.
In other words, find $\displaystyle{\sum_{i=1}^{N-1}\sum_{j=i+1}^{N} |A_i-A_j|}$.
Constraints
- $2 \leq N \leq 2 \times 10^5$
- $|A_i|\leq 10^8$
- $A_i$ is an integer.
Input
Input is given from Standard Input in the following format:
$N$ $A_1$ $\ldots$ $A_N$
Output
Print the answer.
Sample Input 1
3 5 1 2
Sample Output 1
8
We have $|5-1|+|5-2|+|1-2|=8$.
Sample Input 2
5 31 41 59 26 53
Sample Output 2
176