304736: CF903D. Almost Difference
Memory Limit:256 MB
Time Limit:2 S
Judge Style:Text Compare
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Description
Almost Difference
题意翻译
- 定义函数 $$d(x,y)=\begin{cases}y-x,&\text{if }|x-y|>1\\0,&\text{if }|x-y|\le 1\end{cases}$$ - 给定长度为 $n$ 的序列 $a$,求 $$\sum_{i=1}^n\sum_{j=i+1}^n d(a_i,a_j)$$ - $1\le n\le 2\times 10^5$,$1\le a_i\le 10^9$。**答案可能会爆 `long long`**。题目描述
Let's denote a function ![](https://cdn.luogu.com.cn/upload/vjudge_pic/CF903D/775e2389c0046855a8c7f1a2f9b05b0f64f8c0ab.png) You are given an array $ a $ consisting of $ n $ integers. You have to calculate the sum of $ d(a_{i},a_{j}) $ over all pairs $ (i,j) $ such that $ 1<=i<=j<=n $ .输入输出格式
输入格式
The first line contains one integer $ n $ ( $ 1<=n<=200000 $ ) — the number of elements in $ a $ . The second line contains $ n $ integers $ a_{1} $ , $ a_{2} $ , ..., $ a_{n} $ ( $ 1<=a_{i}<=10^{9} $ ) — elements of the array.
输出格式
Print one integer — the sum of $ d(a_{i},a_{j}) $ over all pairs $ (i,j) $ such that $ 1<=i<=j<=n $ .
输入输出样例
输入样例 #1
5
1 2 3 1 3
输出样例 #1
4
输入样例 #2
4
6 6 5 5
输出样例 #2
0
输入样例 #3
4
6 6 4 4
输出样例 #3
-8