简单ｄｆｓ 对于每个数 两种情况 取还是不取
#include <iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<stdlib.h>
#include<map>
#include<string>
using namespace std;
map<string,int>f;
struct node
{
int a,b,c;
}p[];
int n,maxz;
int vis[];
int judge(node x,node y)
{
if(x.a==y.b||x.a==y.a||x.a==y.c)
return ;
if(x.b==y.b||x.b==y.a||x.b==y.c)
return ;
if(x.c==y.b||x.c==y.a||x.c==y.c)
return ;
return ;
}
void dfs(int v,int u)
{
maxz = max(maxz,v);
if(u>n)
return ;
if(!vis[p[u].a]&&!vis[p[u].b]&&!vis[p[u].c])
{
vis[p[u].a] = vis[p[u].b] = vis[p[u].c] = ;
dfs(v+,u+);
vis[p[u].a] = vis[p[u].b] = vis[p[u].c] = ;
}
dfs(v,u+);
}
int main()
{
int i,g=;
char s1[],s2[],s3[];
scanf("%d",&n);
for(i = ;i <= n ; i++)
{
scanf("%s%s%s",s1,s2,s3);
if(!f[s1])
{
g++;
f[s1] = g;
}
if(!f[s2])
{
g++;
f[s2] = g;
}
if(!f[s3])
{
g++;
f[s3] = g;
}
p[i].a = f[s1];
p[i].b = f[s2];
p[i].c = f[s3];
}
for(i = ;i <= n ; i++)
{
vis[p[i].a] = vis[p[i].b] = vis[p[i].c] = ;
dfs(,i+);
vis[p[i].a] = vis[p[i].b] = vis[p[i].c] = ;
}
printf("%d\n",maxz);
return ;
}