HDU5069(AC自动机+线段树)

题意：http://acm.hdu.edu.cn/showproblem.php?pid=5069

给你n个串，m个询问：以b串的前缀和a串的后缀最长是多少。

思路：https://blog.csdn.net/gatevin/article/details/46123703

讲的很全面了。

#define IOS ios_base::sync_with_stdio(0); cin.tie(0);
#include <cstdio>//sprintf islower isupper
#include <cstdlib>//malloc  exit strcat itoa system("cls")
#include <iostream>//pair
#include <fstream>//freopen("C:\Users\13606\Desktop\Input.txt","r",stdin);
#include <bitset>
//#include <map>
//#include<unordered_map>
#include <vector>
#include <stack>
#include <set>
#include <string.h>//strstr substr strcat
#include <string>
#include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9;
#include <cmath>
#include <deque>
#include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less
#include <vector>//emplace_back
//#include <math.h>
#include <cassert>
#include <iomanip>
//#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor
#include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare)
using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation
//******************
clock_t __START,__END;
double __TOTALTIME;
void _MS(){__START=clock();}
void _ME(){__END=clock();__TOTALTIME=(double)(__END-__START)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;}
//***********************
#define rint register int
#define fo(a,b,c) for(rint a=b;a<=c;++a)
#define fr(a,b,c) for(rint a=b;a>=c;--a)
#define mem(a,b) memset(a,b,sizeof(a))
#define pr printf
#define sc scanf
#define ls rt<<1
#define rs rt<<1|1
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef unsigned long long ull;
typedef long long ll;
typedef double db;
const db E=2.718281828;
const db PI=acos(-1.0);
const ll INF=(1LL<<60);
const int inf=(1<<30);
const db ESP=1e-9;
const int mod=(int)1e9+7;
const int N=(int)2e5+10;

char s[N];
int in_id[N];
struct node
{
    int l,r;
}P[N];

ll max_[N<<2],add[N<<2];

void up(int rt,int l,int r){
    max_[rt]=max(max_[ls],max_[rs]);
}
void dn(int rt){
    if(add[rt]!=0)
    {
        max_[ls]=max(max_[ls],add[rt]);
        max_[rs]=max(max_[rs],add[rt]);
        add[ls]=max(add[ls],add[rt]);
        add[rs]=max(add[rs],add[rt]);
        add[rt]=0;
    }
}
void Build(int l,int r,int rt)
{
    max_[rt]=0;
    add[rt]=0;
    if(l==r)
    {
        return;
    }
    int mid=(l+r)>>1;

    Build(l,mid,rt<<1);
    Build(mid+1,r,rt<<1|1);
    up(rt,l,r);
}
ll query_dot(int pos,int l,int r,int rt)
{
    if(l==r)
    {
        return max_[rt];
    }

    int mid=(l+r)>>1;
    dn(rt);
    if(pos<=mid)
        return query_dot(pos,l,mid,rt<<1);
    else
        return query_dot(pos,mid+1,r,rt<<1|1);
}
void update_qu(int L,int R,ll V,int l,int r,int rt)
{
    if(L>R)return;
    if(L<=l&&r<=R)
    {
        max_[rt]=max(max_[rt],V);
        add[rt]=max(add[rt],V);
        return;
    }

    int mid=(l+r)>>1;
    dn(rt);
    if(L<=mid)
        update_qu(L,R,V,l,mid,rt<<1);
    if(R>mid)
        update_qu(L,R,V,mid+1,r,rt<<1|1);
    up(rt,l,r);
}
//-----------------------线段树
//====================================================================
class MAP
{
public:
    struct EDGE
    {
        int to,next;
    }edge[N];

    int tot;
    int head[N];

    int dfn[N],DFN,SZ[N];
    void Init(int n)
    {
        tot=DFN=0;
        for(int i=0;i<=n;++i)
            head[i]=SZ[i]=dfn[i]=0;
    }
    void add(int from,int to)
    {
        ++tot;
        edge[tot].to=to;
        edge[tot].next=head[from];
        head[from]=tot;
    }
    int dfs(int u,int fa)
    {
        dfn[u]=++DFN;
        SZ[dfn[u]]=1;
        for(int i=head[u];i;i=edge[i].next)
        {
            int to=edge[i].to;
            if(to!=fa)
                SZ[dfn[u]]+=dfs(to,u);
        }
        return SZ[dfn[u]];
    }
}mp;
//====================================================================
//------------------------AC
class ac_automaton//失配时,尽可能长得保留后缀以重新开始匹配.
{
public:
    int tot;
    int trie[N][27];
    int fail[N];
    //other
    //--------------
    void Init(int n)
    {
        tot=0;
        for(int i=0;i<=n;++i)
        {
            fail[i]=0;
            for(int j=1;j<=26;++j)
                trie[i][j]=0;
        }
    }
    int Insert(int l,int r)
    {
        int rt=0;
        for(int i=l;i<=r;++i)
        {
            int id=s[i]-'A'+1;
            if(!trie[rt][id])trie[rt][id]=++tot;
            rt=trie[rt][id];
        }
        return rt;
    }
    void Getfail()
    {
        queue<int>q;
        for(int i=1;i<=26;++i)
        {
            int id=trie[0][i];
            if(id)
            {
                fail[id]=0;
                q.push(id);
            }
        }
        while(!q.empty())
        {
            int rt=q.front();q.pop();
            for(int i=1;i<=26;++i)
            {
                int id=trie[rt][i];
                if(id)
                {
                    fail[id]=trie[fail[rt]][i];
                    q.push(id);
                }
                else
                    trie[rt][i]=trie[fail[rt]][i];
            }
        }
    }
    void Find(int l,int r,ll sgm)
    {
        int rt=0;
        for(int i=l;i<=r;++i)
        {
            rt=trie[rt][s[i]-'A'+1];
            int pos=mp.dfn[rt];
            update_qu(pos,pos+mp.SZ[pos]-1,i-l+1+sgm,1,tot+1,1);
        //    for(int j=1;j<=tot+1;++j)check(j,1,tot+1,1);
        //    cout<<endl;
        }
    }
}AC;

struct GG
{
    int id,to_a;
};
vector<vector<GG> >G(N);
ll ans[N];
int aa[N],bb[N];

int main()
{
//    freopen("C:\Users\13606\Desktop\Input.txt","r",stdin);
//    freopen("C:\Users\13606\Desktop\1.txt","w",stdout);
    int n,m;
    while(~sc("%d%d",&n,&m))
    {
        for(int i=1;i<=n;++i)G[i].clear();
        int len=0;
        for(int i=1;i<=n;++i)
        {
            sc("%s",s+1+len);
            P[i].l=1+len;
            len+=strlen(s+1+len);
            P[i].r=len;
        }
        AC.Init(len);
        for(int i=1;i<=n;++i)
            in_id[i]=AC.Insert(P[i].l,P[i].r);
        AC.Getfail();
        int tot=AC.tot+1;
        Build(1,tot,1);

        for(int i=1;i<=m;++i)
        {
            int a,b;
            sc("%d%d",&a,&b);
            aa[i]=a,bb[i]=b;
            G[b].push_back({i,a});
        }
        mp.Init(tot);
        for(int i=1;i<=AC.tot;i++)
        {
            mp.add(i,AC.fail[i]);
            mp.add(AC.fail[i],i);
        }
        mp.dfs(0,-1);
        ll sgm=-100000000;
        for(int i=1;i<=n;++i)
        {
            sgm+=100000000;
            AC.Find(P[i].l,P[i].r,sgm);
            int sz=G[i].size();
            for(int j=0;j<sz;++j)
            {
                GG now=G[i][j];
                ans[now.id]=max(0LL,query_dot(mp.dfn[in_id[now.to_a]],1,tot,1)-sgm);
            }
        }
        for(int i=1;i<=m;++i)
            pr("%lld
",ans[i]);
    }
    return 0;
}

/**************************************************************************************/