题目描述
Problem Statement
Given is a sequence A of N integers. There are 2^N - 1 non-empty subsequences B of A. Find the sum of $\max\left(B\right) \times \min\left(B\right)$ over all of them.
Since the answer can be enormous, report it modulo 998244353.
Input
Input is given from Standard Input in the following format:
N
$A_1 A_2 \cdots A_N$
Output
Print the answer.
Constraints
- All values in input are integers.
- $1 \leq N \leq 2 \times 10^5$
- $0 \leq A_i \leq 998244352$
Sample Input 1
3
2 4 3
Sample Output 1
63
There are 7 subsequences B, as follows:
- $B = \left(2\right)$ : $\max\left(B\right) \times \min\left(B\right) = 4$
- $B = \left(4\right)$ : $\max\left(B\right) \times \min\left(B\right) = 16$
- $B = \left(3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 9$
- $B = \left(2, 4\right)$ : $\max\left(B\right) \times \min\left(B\right) = 8$
- $B = \left(2, 3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 6$
- $B = \left(4, 3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 12$
- $B = \left(2, 4, 3\right)$ : $\max\left(B\right) \times \min\left(B\right) = 8$
The answer is the sum of them: 63.
Sample Input 2
1
10
Sample Output 2
100
Sample Input 3
7
853983 14095 543053 143209 4324 524361 45154
Sample Output 3
206521341
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
3
2 4 3
样例输出
63