A11562. Almost Difference
编程题
普及/提高-
知识点
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 $1<=i<=j<=n$ .
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.
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:
1. $d(a_{1},a_{2})=0$ ;
2. $d(a_{1},a_{3})=2$ ;
3. $d(a_{1},a_{4})=0$ ;
4. $d(a_{1},a_{5})=2$ ;
5. $d(a_{2},a_{3})=0$ ;
6. $d(a_{2},a_{4})=0$ ;
7. $d(a_{2},a_{5})=0$ ;
8. $d(a_{3},a_{4})=-2$ ;
9. $d(a_{3},a_{5})=0$ ;
10. $d(a_{4},a_{5})=2$ .
1. $d(a_{1},a_{2})=0$ ;
2. $d(a_{1},a_{3})=2$ ;
3. $d(a_{1},a_{4})=0$ ;
4. $d(a_{1},a_{5})=2$ ;
5. $d(a_{2},a_{3})=0$ ;
6. $d(a_{2},a_{4})=0$ ;
7. $d(a_{2},a_{5})=0$ ;
8. $d(a_{3},a_{4})=-2$ ;
9. $d(a_{3},a_{5})=0$ ;
10. $d(a_{4},a_{5})=2$ .