HDU-1087(Super Jumping! Jumping! Jumping!)

Problem Description

Nowadays, a kind of chess game called “Super Jumping! Jumping! Jumping!” is very popular in HDU. Maybe you are a good boy, and know little about this game, so I introduce it to you now.



The game can be played by two or more than two players. It consists of a chessboard（棋盘）and some chessmen（棋子）, and all chessmen are marked by a positive integer or “start” or “end”. The player starts from start-point and must jumps into end-point finally. In
the course of jumping, the player will visit the chessmen in the path, but everyone must jumps from one chessman to another absolutely bigger (you can assume start-point is a minimum and end-point is a maximum.). And all players cannot go backwards. One jumping
can go from a chessman to next, also can go across many chessmen, and even you can straightly get to end-point from start-point. Of course you get zero point in this situation. A player is a winner if and only if he can get a bigger score according to his
jumping solution. Note that your score comes from the sum of value on the chessmen in you jumping path.

Your task is to output the maximum value according to the given chessmen list.

Input

Input contains multiple test cases. Each test case is described in a line as follow:

N value_1 value_2 …value_N

It is guarantied that N is not more than 1000 and all value_i are in the range of 32-int.

A test case starting with 0 terminates the input and this test case is not to be processed.

Output

For each case, print the maximum according to rules, and one line one case.

Sample Input

3 1 3 2

4 1 2 3 4

4 3 3 2 1

0

Sample Output

4

10

3

简单DP题，求最长递增子序列，dp[i]表示到第i个数的最优值，

首先要想到DP的性质：最优子结构，即全局最优解的局部也是最优解；

主要思路是后边每一步要根据前边已求的最优解推出；

状态转移方程：dp[i]=max{dp[j]+a[i],dp[i]}（前提是a[i]>a[j]）,意思是如果第i个数比第j个数大，就可以直接从第i个数跳到第j个数，

判断到第j个数时的最优解加上第i个数是否比当前到第i个数时的最优解大；

#include<stdio.h>
int max (int a,int b)
{
return a>b?a:b;
}
int main ()
{
int a[1005],dp[1005];
int i,j,n;
int sum;
while (scanf ("%d",&n),n)
{
for (i=0;i<n;i++)
{
scanf ("%d",&a[i]);
}
dp[0]=a[0];
sum=dp[0];
for (i=1;i<n;i++)
{
dp[i]=a[i];
for (j=0;j<i;j++)
{
if (a[i]>a[j])
dp[i]=max(dp[j]+a[i],dp[i]);
}
if (dp[i]>sum)
sum=dp[i];
}
printf ("%d\n",sum);
}
return 0;
}