TRT - Treats for the Cows

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.

Input

Line 1: A single integer, N

Lines 2..N+1: Line i+1 contains the value of treat v(i)

Output

The maximum revenue FJ can achieve by selling the treats

Example

Input:
5
1
3
1
5
2

Output:
43

Added by:Nguyen Van Quang Huy
Date:2006-02-15
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: NODEJS PERL6 VB.NET
Resource:USACO FEB06 Gold Division

hide comments
2014-09-22 14:27:12 Kishlay Raj
my 50th cakewalk :P
2014-09-20 16:50:58 Deepanker Aggarwal
50th :)...Btw any clues on how can this be done iteratively?
2014-09-13 19:54:33 Arun Karthikeyan
Java Recursion TLE, same soln AC in C++
Java Iteration DP AC.
2014-09-07 11:47:38 Gaurav Ahirwar
AC in go! cakewalk dp! :) :D ..
2014-08-30 18:56:45 S
:S :D first attempt
2014-08-16 19:54:53 tushar aggarwal
got it in 1st attempt :)
2014-08-09 19:17:56 kernel
Instead of thinking it in terms of pure DP its better to approach the problem with recursion(TOPDOWN) with memoization...... AC

6 | 6 1 1 1 5 5 . Ans = 70 <- Greedy approach fails
5 | 1 3 1 5 2 . Ans = 43 <- Greedy approach works


Last edit: 2014-08-09 19:37:32
2014-08-08 16:19:44 AmirShams
nice

Last edit: 2014-08-08 16:20:38
2014-07-30 16:50:17 Krishna Nakkeeran
My sol first got sigsegv but wen i submitted by declaring the array globally it got acc can anyone explain this
2014-07-22 04:28:32 Darren Sun
Good problem. I solved it with O(n^2) time and O(n) space. Is it optimal in terms of time and space complexity?
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