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; }