[HEOI2012]旅行问题 AC 自动机

Code:

#include <bits/stdc++.h>
#define ll long long
#define setIO(s) freopen(s".in","r",stdin)
using namespace std;
const int maxn=1000007;
const ll mod=1000000007;
queue<int>q;
vector<int>get[maxn];
ll id[maxn];
char str[maxn];
int edges,tot;
int ch[maxn][30],f[maxn],hd[maxn],to[maxn],nex[maxn],dep[maxn],top[maxn],son[maxn],siz[maxn],fa[maxn];
inline void addedge(int u,int v){ nex[++edges]=hd[u],hd[u]=edges,to[edges]=v;  }
inline void insert(int idx,char ss[])
{
    int x=0,len=strlen(ss+1),i;
    for(i=1;i<=len;++i)
    {
        int c=ss[i]-'a';
        if(!ch[x][c]) { ch[x][c]=++tot,id[ch[x][c]]=(1ll*26*id[x]+c)%mod; }
        x=ch[x][c];
        get[idx].push_back(x);
    }
}
inline void getfail()
{
    int i,j;
    for(i=0;i<27;++i) if(ch[0][i]) addedge(0,ch[0][i]),q.push(ch[0][i]);
    while(!q.empty())
    {
        int u=q.front();q.pop();
        for(i=0;i<27;++i)
        {
            int p=ch[u][i];
            if(!p) { ch[u][i]=ch[f[u]][i]; continue;  }
            f[p]=ch[f[u]][i], addedge(f[p],p);
            q.push(p);
        }
    }
}
void dfs1(int u,int ff)
{
    int i;
    fa[u]=ff,siz[u]=1;
    for(i=hd[u];i;i=nex[i])
    {
        int v=to[i];
        if(v==ff) continue;
        dep[v]=dep[u]+1,dfs1(v,u), siz[u]+=siz[v];
        if(siz[v]>siz[son[u]]) son[u]=v;
    }
}
void dfs2(int u,int tp)
{
    int i;
    top[u]=tp;
    if(son[u]) dfs2(son[u],tp);
    for(i=hd[u];i;i=nex[i])
    {
        int v=to[i];
        if(v==fa[u]||v==son[u]) continue;
        dfs2(v,v);
    }
}
int LCA(int x,int y)
{
    while(top[x]^top[y])
    {
        dep[top[x]]>dep[top[y]]?x=fa[top[x]]:y=fa[top[y]];
        // printf("%d %d\n",x,y);
    }
    return dep[x]<dep[y]?x:y;
}
int main()
{
    // setIO("input");
    int n,i,j,m;
    scanf("%d",&n);
    for(i=1;i<=n;++i) scanf("%s",str+1),insert(i,str);
    getfail(),dfs1(0,-1),dfs2(0,0);
    scanf("%d",&m);
    for(i=1;i<=m;++i)
    {
        int a,b,c,d;
        scanf("%d%d%d%d",&a,&b,&c,&d);
        printf("%lld\n",id[LCA(get[a][b-1], get[c][d-1])]);
    }
    return 0;
}