浅谈AC自动机

#include<iostream>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#define ll long long
#define INF 2147483647
#define mem(i,j) memset(i,j,sizeof(i))
#define F(i,j,n) for(register int i=j;i<=n;i++)
using namespace std;
int n,sn[1000010][28],cnt=0;
int num[1000010],Next[1000010];
char s1[1000010],s2[1000010];
int lst[1000010];
inline int read(){
    int datta=0;char chchc=getchar();bool okoko=0;
    while(chchc<'0'||chchc>'9'){if(chchc=='-')okoko=1;chchc=getchar();}
    while(chchc>='0'&&chchc<='9'){datta=datta*10+chchc-'0';chchc=getchar();}
    return okoko?-datta:datta;
}
struct AC_Automaton{
    void ins(){
        int now=0,len=strlen(s1+1);
        F(p,1,len){
            if(!sn[now][s1[p]-'a'+1])
                sn[now][s1[p]-'a'+1]=++cnt;
            now=sn[now][s1[p]-'a'+1];
        }
        num[now]++;
    }
    void get_Next(){
        int hd=1,tl=0;
        F(p,1,26)
            if(sn[0][p])
                lst[++tl]=sn[0][p];
        while(hd<=tl){
            int now=lst[hd];
            F(p,1,26)
                if(!sn[now][p])
                    sn[now][p]=sn[Next[now]][p];
                else{
                    Next[sn[now][p]]=sn[Next[now]][p];
                    lst[++tl]=sn[now][p];
                }
            hd++;
        }
    }
    int ask(){
        int now=0,res=0,len=strlen(s2+1);
        F(p,1,len){
            now=sn[now][s2[p]-'a'+1];
            int tnow=now;
            while(tnow!=0&&num[tnow]!=-1){
                res+=num[tnow];
                num[tnow]=-1;
                tnow=Next[tnow];
            }
        }
        return res;
    }
}ac;
int main(){
    n=read();
    F(i,1,n)
        scanf("%s",s1+1),ac.ins();
    ac.get_Next();
    scanf("%s",s2+1);
    printf("%d",ac.ask());
    return 0;
}

原文地址：https://www.cnblogs.com/hzf29721/p/10255641.html