CF903D.Almost Difference

普及/提高-

通过率：0%

AC君温馨提醒

该题目为【codeforces】题库的题目，您提交的代码将被提交至codeforces进行远程评测，并由ACGO抓取测评结果后进行展示。由于远程测评的测评机由其他平台提供，我们无法保证该服务的稳定性，若提交后无反应，请等待一段时间后再进行重试。

题目描述

Let's denote a function

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#1
```
5
1 2 3 1 3
```
输出#1
```
4
```
输入#2
```
4
6 6 5 5
```
输出#2
```
0
```
输入#3
```
4
6 6 4 4
```
输出#3
```
-8
```

说明/提示

In the first example:

$d(a_{1},a_{2})=0$ ;
$d(a_{1},a_{3})=2$ ;
$d(a_{1},a_{4})=0$ ;
$d(a_{1},a_{5})=2$ ;
$d(a_{2},a_{3})=0$ ;
$d(a_{2},a_{4})=0$ ;
$d(a_{2},a_{5})=0$ ;
$d(a_{3},a_{4})=-2$ ;
$d(a_{3},a_{5})=0$ ;
$d(a_{4},a_{5})=2$ .

首页