TWENDS  Two Ends
In the twoplayer game “Two Ends”, an even number of cards is laid out in a row. On each card, face up, is written a positive integer. Players take turns removing a card from either end of the row and placing the card in their pile. The player whose cards add up to the highest number wins the game. Now one strategy is to simply pick the card at the end that is the largest — we’ll call this the greedy strategy. However, this is not always optimal, as the following example shows: (The first player would win if she would first pick the 3 instead of the 4.)
3 2 10 4
You are to determine exactly how bad the greedy strategy is for different games when the second player uses it but the first player is free to use any strategy she wishes.
Input
There will be multiple test cases. Each test case will be contained on one line. Each line will start with an even integer n followed by n positive integers. A value of n = 0 indicates end of input. You may assume that n is no more than 1000. Furthermore, you may assume that the sum of the numbers in the list does not exceed 1,000,000.
Output
For each test case you should print one line of output of the form:
In game m, the greedy strategy might lose by as many as p points.
where m is the number of the game (starting at game 1) and p is the maximum possible difference between the first player’s score and second player’s score when the second player uses the greedy strategy. When employing the greedy strategy, always take the larger end. If there is a tie, remove the left end.
Example
Input: 4 3 2 10 4 8 1 2 3 4 5 6 7 8 8 2 2 1 5 3 8 7 3 0 Output: In game 1, the greedy strategy might lose by as many as 7 points. In game 2, the greedy strategy might lose by as many as 4 points. In game 3, the greedy strategy might lose by as many as 5 points.
hide comments
da_201501181:
20170521 14:02:18
NOTE: "If there is a tie, remove the left end." caused me 1 WA..


vengatesh15:
20170405 18:00:03
don't forget to consider i.e in greedy approach if both end have same value then take the left end that cost me 2 WA 

nilabja16180:
20170321 19:37:31
DP with RECURSION, AC IN ONE GO! 0.00 sec Last edit: 20170321 19:38:14 

ruben_ash:
20170228 17:49:22
Solve for the good strategy with dp + memoization, and try to find the greedy answer in O(1). 

gautam:
20170223 10:40:18
bcz of == got too many wa..but finally Ac ..;) 

starbot:
20170211 13:45:06
used map for memoization..TLE, then used array..AC 

mkfeuhrer:
20170130 18:12:01
Try spoj TRT before this :) AC :) 

epsilonalpha:
20161222 01:16:24
0.02s in C++! AC in one go!


siddharth_0196:
20161005 13:22:41
Recursion + Memoization = AC!


alaa_alrayes96:
20160927 22:00:14
recursion + momization make sure that if equal remove from the left side

Added by:  Camilo Andrés Varela León 
Date:  20070726 
Time limit:  0.100s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  East Central North America 2005 