hdu 4597 Play Game

经典区间dp，两摞牌，分别可以从每一摞牌上面和下面取一张牌

 

#include <cstdio>

#include <cstring>

int dp[23][23][23][23];

int arr[2][23];

int max(int x,int y)

{

    return x>y?x:y;

}

int dfs(int x1,int y1,int x2,int y2)

{

    if(x1>y1&&x2>y2) return 0;

    if(dp[x1][y1][x2][y2]) return dp[x1][y1][x2][y2];

    int v=0,sum=arr[0][y1]-arr[0][x1-1]+arr[1][y2]-arr[1][x2-1];



    if(x1<=y1)

    {

        v=max(v,sum-dfs(x1+1,y1,x2,y2));

        v=max(v,sum-dfs(x1,y1-1,x2,y2));

    }

    if(x2<=y2)

    {

        v=max(v,sum-dfs(x1,y1,x2+1,y2));

        v=max(v,sum-dfs(x1,y1,x2,y2-1));

    }

    return dp[x1][y1][x2][y2]=v;

}

int main()

{

//    freopen("in.txt","r",stdin);

    int t,n,x;

    scanf("%d",&t);

    while(t--)

    {

        scanf("%d",&n);

        arr[0][0]=arr[1][0]=0;

        for(int i=0; i<2; ++i)

            for(int j=1; j<=n; ++j)

            {

                scanf("%d",&x);

                arr[i][j]=x+arr[i][j-1];

            }

        memset(dp,0,sizeof(dp));

        printf("%d\n",dfs(1,n,1,n));

    }

    return 0;

}