问题2965--Treats for the Cows

2965: Treats for the Cows

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时间限制 : 1.000 sec  内存限制 : 64 MB

题目描述

FJ has purchased N (1 <= N <= 2000) yummy treats for the cows who get money for giving vast amounts of milk. FJ sells one treat per day and wants to maximize the money he receives over a given period time. The treats are interesting for many reasons: * The treats are numbered 1..N and stored sequentially in single file in a long box that is open at both ends. On any day, FJ can retrieve one treat from either end of his stash of treats. * Like fine wines and delicious cheeses, the treats improve with age and command greater prices. * The treats are not uniform: some are better and have higher intrinsic value. Treat i has value v(i) (1 <= v(i) <= 1000). * Cows pay more for treats that have aged longer: a cow will pay v(i)*a for a treat of age a. Given the values v(i) of each of the treats lined up in order of the index i in their box, what is the greatest value FJ can receive for them if he orders their sale optimally? The first treat is sold on day 1 and has age a=1. Each subsequent day increases the age by 1.

输入

* Line 1: A single integer, N * Lines 2..N+1: Line i+1 contains the value of treat v(i)

输出

* Line 1: The maximum revenue FJ can achieve by selling the treats

样例输入 Copy

5
1
3
1
5
2

样例输出 Copy

43

提示

INPUT DETAILS: Five treats. On the first day FJ can sell either treat #1 (value 1) or treat #5 (value 2). OUTPUT DETAILS: FJ sells the treats (values 1, 3, 1, 5, 2) in the following order of indices: 1, 5, 2, 3, 4, making 1x1 + 2x2 + 3x3 + 4x1 + 5x5 = 43.

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