UVA10891 Game of Sum

题意:两个人A,B玩游戏，轮流玩，A 先取，每个人每次只准在右边或左边拿1个或多个数，每个人都采取最优策略尽量让自己的得分高

问A-B的最大值

// File Name: 10891.cpp
// Author: zlbing
// Created Time: 2013/1/23 17:46:22

#include<iostream>
#include<string>
#include<algorithm>
#include<cstdlib>
#include<cstdio>
#include<set>
#include<map>
#include<vector>
#include<cstring>
#include<stack>
using namespace std;
#define MAXN 105
int A[MAXN];
int S[MAXN];
bool vis[MAXN][MAXN];
int d[MAXN][MAXN];
int dp(int i,int j)
{
    if(vis[i][j])return d[i][j];
    vis[i][j]=true;
    int ans=0;
    for(int k=i+1;k<=j;k++)
        ans=min(dp(k,j),ans);
    for(int k=i;k<j;k++)
        ans=min(dp(i,k),ans);
    d[i][j]=S[j]-S[i-1]-ans;
    return d[i][j];
}
int main(){
    int n;
    while(~scanf("%d",&n))
    {
        if(!n)break;
        S[0]=0;
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&A[i]);
            S[i]=S[i-1]+A[i];
        }    
        memset(vis,false,sizeof(vis));
        int k=dp(1,n);
        printf("%d\n",2*k-S[n]);
    }
    return 0;
}