【DP 训练】Free Candies, UVa 10118

#include<bits/stdc++.h>
using namespace std;
int n,dp[50][50][50][50],pile[5][50],top[5];
int dfs(int cur,int status)
{
if(cur==5)return 0;
int& ans = dp[top[1]][top[2]][top[3]][top[4]];
if(ans!=-1)return ans;
ans = 0;
for(int i=1;i<=4;i++)
{
if(top[i]==n)continue;
++top[i];
if(status&1<<pile[i][top[i]])
ans = max(ans,dfs(cur-1,status^1<<pile[i][top[i]])+1);
else ans = max(ans,dfs(cur+1,status^1<<pile[i][top[i]]));
--top[i];
}
return ans;
}
int main(void)
{
while(scanf("%d",&n)&&n)
{
for(int i=1;i<=n;i++)
{
for(int j=1;j<=4;j++)
{
cin>>pile[j][i];
}
}
memset(top,0,sizeof(top));
memset(dp,-1,sizeof(dp));
cout<<dfs(0,0)<<endl;
}
return 0;
}