uva 10118 Free Candies

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;int vis[30],top[5],dp[60][60][60][60],n,d[4][60];int dfs(int k){int &t=dp[top[0]][top[1]][top[2]][top[3]];if(t != -1) return t;t=0;if(k >= 5 || top[0]+top[1]+top[2]+top[3] == n * 4) return t;for(int i=0;i<4;i++){if(top[i] >= n) continue;top[i]++;if(vis[d[i][top[i]]]){vis[d[i][top[i]]]=0;t=max(dfs(k-1)+1,t);vis[d[i][top[i]]]=1;}else{vis[d[i][top[i]]]=1;t=max(dfs(k+1),t);vis[d[i][top[i]]]=0;}top[i]--;}return t;}int main(){while(scanf("%d",&n) == 1 && n){for(int i = 1;i <= n; i++){for(int j = 0;j < 4; j++){scanf("%d",&d[j][i]);}}memset(vis,0,sizeof(vis));memset(top,0,sizeof(top));memset(dp,-1,sizeof(dp));printf("%d\n",dfs(0));}}