【bzoj2938】病毒 AC自动机

AC通道：http://www.lydsy.com/JudgeOnline/problem.php?id=2938

【题解】

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<cmath>
#include<algorithm>
using namespace std;
int n,cnt(1),end[30010],size[30010],q[30010],fail[30010],ins[30010],vis[30010],tr[30010][2];
char ch[30010];
inline int read()
{
int x=0,f=1;  char ch=getchar();
while(!isdigit(ch))  {if(ch=='-')  f=-1;  ch=getchar();}
while(isdigit(ch))  {x=x*10+ch-'0';  ch=getchar();}
return x*f;
}
void Insert()
{
int now=0,l=strlen(ch+1);
for(int i=1;i<=l;i++)
{
if(!tr[now][ch[i]-'0']) tr[now][ch[i]-'0']=++cnt;
now=tr[now][ch[i]-'0'];
}
end[now]=1;
}
void build()
{
int head=0,tail=0;
for(int i=0;i<=1;i++)  if(tr[0][i])  q[++tail]=tr[0][i];
while(++head<=tail)
{
int x=q[head];
for(int i=0;i<=1;i++)
{
int y=tr[x][i];
if(!y){tr[x][i]=tr[fail[x]][i];continue;}
q[++tail]=y;
int temp=fail[x];
while(!tr[temp][i]) temp=fail[temp];
fail[y]=tr[temp][i];
end[y]|=end[tr[temp][i]];
}
}
}
bool dfs(int x)
{
ins[x]=1;
for(int i=0;i<2;i++)
{
int v=tr[x][i];
if(ins[v])return 1;
if(vis[v]||end[v])continue;
vis[v]=1;
if(dfs(v))return 1;
}
ins[x]=0;
return 0;
}
int main()
{
//freopen("cin.in","r",stdin);
//freopen("cout.out","w",stdout);
n=read();
for(int i=1;i<=n;i++)  {scanf("%s",ch+1);  Insert();}
build();
if(dfs(0))  printf("TAK\n");
else printf("NIE\n");
return 0;
}