题目描述
Problem Statement
You are given a sequence of integers $A=(A_1,\ldots,A_N)$. For a tree T with N vertices, define f(T) as follows:
- Let d_i be the degree of vertex i in $T. Then, f(T)=\sum_{i=1}^N {d_i}^2 A_i$.
Find the minimum possible value of f(T).
The constraints guarantee the answer to be less than 2^{63}.
Input
The input is given from Standard Input in the following format:
N
$A_1 A_2 \ldots A_N$
Output
Print the answer.
Constraints
- $2\leq N\leq 2\times 10^5$
- $1\leq A_i \leq 10^9$
- All input values are integers.
Sample Input 1
4
3 2 5 2
Sample Output 1
24
Consider a tree T with an edge connecting vertices 1 and 2, an edge connecting vertices 2 and 4, and an edge connecting vertices 4 and 3.
Then, $f(T) = 1^2\times 3 + 2^2\times 2 + 1^2\times 5 + 2^2\times 2 = 24$. It can be proven that this is the minimum value of f(T).
Sample Input 2
3
4 3 2
Sample Output 2
15
Sample Input 3
7
10 5 10 2 10 13 15
Sample Output 3
128
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分