AC自动机

Posted 2020-06-20 __560

手写了下AC自动机，真正理解了kmp之后手写AC自动机还是很简单的。。。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<queue>
#define REP(i,a,b) for(int i=a;i<=b;i++)
#define MS0(a) memset(a,0,sizeof(a))

using namespace std;

typedef long long ll;
const int maxn=1000100;
const int INF=1e9+10;

struct Trie
{
    int ch[maxn][26];
    int End[maxn];
    int f[maxn];
    int last[maxn];
    int rt,L;
    int newnode()
    {
        ++L;
        memset(ch[L],-1,sizeof(ch[L]));
        End[L]=0;
        return L;
    }
    void init()
    {
        L=-1;
        rt=newnode();
    }
    void insert(char *s)
    {
        int len=strlen(s);
        int u=rt;
        REP(i,0,len-1){
            int c=s[i]-‘a‘;
            if(ch[u][c]==-1) ch[u][c]=newnode();
            u=ch[u][c];
        }
        End[u]++;
    }
    int get(int u)
    {
        if(!u) return 0;
        int res=End[u]+get(last[u]);
        End[u]=0;
        return res;
    }
    int find(char *s)
    {
        int res=0;
        int len=strlen(s);
        int u=rt;
        REP(i,0,len-1){
            int c=s[i]-‘a‘;
            u=ch[u][c];
            if(End[u]) res+=get(u);
            else if(last[u]) res+=get(last[u]);
        }
        return res;
    }
    void build()
    {
        queue<int> q;
        REP(c,0,25){
            if(~ch[rt][c]) q.push(ch[rt][c]),f[ch[rt][c]]=rt;
            else ch[rt][c]=rt;
        }
        while(!q.empty()){
            int u=q.front();q.pop();
            last[u]=rt;
            REP(c,0,25){
                if(~ch[u][c]) f[ch[u][c]]=ch[f[u]][c],q.push(ch[u][c]);
                else ch[u][c]=ch[f[u]][c];
                if(End[f[u]]) last[u]=f[u];
                else last[u]=last[f[u]];
            }
        }
    }
};Trie ac;
int n;
char s[maxn],t[maxn];

int main()
{
    #ifndef ONLINE_JUDGE
        freopen("in.txt","r",stdin);
    #endif // ONLINE_JUDGE
    int T;cin>>T;
    while(T--){
        scanf("%d",&n);
        ac.init();
        REP(i,1,n){
            scanf("%s",t);
            ac.insert(t);
        }
        ac.build();
        scanf("%s",s);
        printf("%d\n",ac.find(s));
    }
    return 0;
}

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