hihoCoder week4 Trie图

ac自动机 

题目链接 https://hihocoder.com/contest/hiho4/problem/1

参考：https://blog.csdn.net/baidu_30541191/article/details/47447175#

#include <iostream>
#include <cstring>
#include <string>
#include <queue>
using namespace std;

struct node 
{
    node *nxt[26], *fail;
    int ok; 
    node() {
        ok = 0;
        for(int i=0; i<26; i++) nxt[i]=NULL;
        fail=NULL;
    }
};

const int N = 1e6 + 10;
char s[N]; 
node *root;

void ins(char *s, int len) 
{
    node *rt = root;
    for(int i=0; i<len; i++) {
        int x= s[i]-'a';
        if(rt->nxt[x] == NULL)
            rt->nxt[x] = new node();
        rt= rt->nxt[x];
    }
    rt->ok = 1;
    return ;
}

void build()
{
    node *rt = root;
    rt->fail = NULL;
    
    queue<node*> que;
    que.push(rt);
    
    while(!que.empty()) {
        node *tmp = que.front();
        que.pop();
        for(int i=0; i<26; i++) {
            if(tmp->nxt[i] != NULL) {
                if(tmp == root) 
                    tmp->nxt[i]->fail = root;
                else {
                    node *p = tmp->fail;
                    while(p!=NULL) {
                        if(p->nxt[i] != NULL) {
                            tmp->nxt[i]->fail = p->nxt[i];
                            break;
                        }
                        p = p->fail;
                    }
                    if(p==NULL) tmp->nxt[i]->fail = root;
                }
                que.push(tmp->nxt[i]);
            }
        }
    }
}

bool query(char *s, int len)
{
    node *rt = root;
    int cnt=0;
    for(int i=0; i<len; i++) {
        int x = s[i]-'a';
        while(!rt->nxt[x] && rt->fail != NULL) 
            rt=rt->fail;
        rt=rt->nxt[x];
        if(!rt) rt = root;
        node * tmp = rt;
        while(tmp->ok==1) {
            cnt++;
            tmp->ok = 0;
            tmp = tmp->fail;
        }
    }
    if(cnt > 0)
        return true;
    return false;
}


int main()
{
    root = new node();
    int n; scanf("%d",&n);
    for(int i=0; i<n; i++) {
        scanf("%s", s), ins(s, strlen(s));
    }
        
    build();
    scanf("%s", s);
    bool ok = query(s,strlen(s));
    if(ok) 
        cout<<"YES"<<endl;
    else 
        cout<<"NO"<<endl;
    return 0;
}