字符串（后缀自动机）：COGS 2399. 循环同构

#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
const int maxn=2000010;
int fa[maxn],len[maxn],rit[maxn],w[maxn],sa[maxn];
int n,Q,cnt,lst,ch[maxn][26],vis[maxn];
char s[maxn];
struct SAM{
SAM(){
memset(fa,0,sizeof(fa));
memset(len,0,sizeof(len));
memset(rit,0,sizeof(rit));
cnt=lst=1;
}

void Insert(int c){
int p=lst,np=lst=++cnt;len[np]=len[p]+1;
while(p&&!ch[p][c])ch[p][c]=np,p=fa[p];
if(!p)fa[np]=1;
else{
int q=ch[p][c];
if(len[p]+1==len[q])fa[np]=q;
else{
int nq=++cnt;len[nq]=len[p]+1;
memcpy(ch[nq],ch[q],sizeof(ch[q]));
fa[nq]=fa[q];fa[q]=fa[np]=nq;
while(ch[p][c]==q)ch[p][c]=nq,p=fa[p];
}
}
}

void Prepare(){
//rit[1]=1;
for(int i=1,p=1;i<=n;i++)
rit[p=ch[p][s[i]-'a']]+=1;
for(int i=1;i<=cnt;i++)w[len[i]]+=1;
for(int i=1;i<=cnt;i++)w[i]+=w[i-1];
for(int i=1;i<=cnt;i++)sa[--w[len[i]]]=i;
for(int i=cnt;i;i--)rit[fa[sa[i]]]+=rit[sa[i]];
}

void Solve(int tim){
scanf("%s",s+1);n=strlen(s+1);
for(int i=1;i<=n;i++)s[n+i]=s[i];
int p=1,ans=0,l=0;
for(int i=1,c;i<2*n;i++){
c=s[i]-'a';
while(p!=1&&!ch[p][c])
{p=fa[p];l=len[p];}
if(!ch[p][c])l=0;
else{p=ch[p][c];l+=1;}

if(l>=n){
while(len[fa[p]]>=n)p=fa[p],l=len[p];
if(vis[p]!=tim)vis[p]=tim,ans+=rit[p];
}
}
printf("%d\n",ans);
}
}sam;
int main(){
freopen("rotate.in","r",stdin);
freopen("rotate.out","w",stdout);
scanf("%s%d",s+1,&Q);n=strlen(s+1);
for(int i=1;i<=n;i++)sam.Insert(s[i]-'a');
sam.Prepare();while(Q--)sam.Solve(Q+1);
return 0;
}