hdu 2222(AC自动机)

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e7 + 5;
const int MAX = 10000000;
int cnt;
struct node{
    node *next[26];
    node *fail;
    int sum;
};
node *root;
char key[70];
node *q[MAX];
int head,tail;
node *newnode;
char pattern[maxn];
int N;
void Insert(char *s)
{
    node *p = root;
    for(int i = 0; s[i]; i++)
    {
        int x = s[i] - 'a';
        if(p->next[x] == NULL)
        {
            newnode=(struct node *)malloc(sizeof(struct node));
            for(int j=0;j<26;j++) newnode->next[j] = 0;
            newnode->sum = 0;newnode->fail = 0;
            p->next[x]=newnode;
        }
        p = p->next[x];
    }
    p->sum++;
}
void build_fail_pointer()
{
    head = 0;
    tail = 1;
    q[head] = root;
    node *p;
    node *temp;
    while(head < tail)
    {
        temp = q[head++];
        for(int i = 0; i <= 25; i++)
        {
            if(temp->next[i])
            {
                if(temp == root)
                {
                    temp->next[i]->fail = root;
                }
                else
                {
                    p = temp->fail;
                    while(p)
                    {
                        if(p->next[i])
                        {
                            temp->next[i]->fail = p->next[i];
                            break;
                        }
                        p = p->fail;
                    }
                    if(p == NULL) temp->next[i]->fail = root;
                }
                q[tail++] = temp->next[i];
            }
        }
    }
}
void ac_automation(char *ch)
{
    node *p = root;
    int len = strlen(ch);
    for(int i = 0; i < len; i++)
    {
        int x = ch[i] - 'a';
        while(!p->next[x] && p != root) p = p->fail;
        p = p->next[x];
        if(!p) p = root;
        node *temp = p;
        while(temp != root)
        {
           if(temp->sum >= 0)
           {
               cnt += temp->sum;
               temp->sum = -1;
           }
           else break;
           temp = temp->fail;
        }
    }
}
int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        root=(struct node *)malloc(sizeof(struct node));
        for(int j=0;j<26;j++) root->next[j] = 0;
        root->fail = 0;
        root->sum = 0;
        scanf("%d",&N);
        for(int i = 1; i <= N; i++)
        {
            scanf("%s",key);
            Insert(key);
        }
        scanf("%s",pattern);
        cnt = 0;
        build_fail_pointer();
        ac_automation(pattern);
        printf("%d
",cnt);
    }
    return 0;
}

大佬的博客：https://blog.csdn.net/creatorx/article/details/71100840

hdu6208

#include<stdio.h>
#include<string.h>
#include<queue>
#include<string>
#include<iostream>
const int maxn = 100005;
using namespace std;

int n;
int nxt[maxn][30],FAIL[maxn],edd[maxn],root,L;
int mark[maxn];

int newnode()
{
    for(int i=0;i<26;i++)
        nxt[L][i] = -1;//节点连接的边初始化为-1
    edd[L]=0;
    mark[L]=0;
    return L++;
}

void init()
{
    L=0;
    root=newnode();
}

void insert(char buf[],int l)//trie树的建立
{
    int now=root;
    for(int i=0;i<l;i++)
    {
        if(nxt[now][buf[i]-'a']==-1)
            nxt[now][buf[i]-'a']=newnode();
        now=nxt[now][buf[i]-'a'];
    }
    edd[now]++;
}

void build()//建立ac自动机
{
    queue<int>que;
    for(int i=0;i<26;i++)
    {
        if(nxt[root][i]==-1)
            nxt[root][i]=root;
        else                                 //若有连边则将节点加入队列 ，并将FAIL指针指向root
        {
            FAIL[nxt[root][i]]=root;
            que.push(nxt[root][i]);
        }
    }
    while(!que.empty())
    {
        int now=que.front();
        que.pop();
        for(int i=0;i<26;i++)
        {
            if(nxt[now][i]==-1)            //若无连边，则将该边指向当前节点FAIL指针指向的相应字符连接的节点
                nxt[now][i]=nxt[FAIL[now]][i];
            else                            //若有连边，则将儿子节点的FAIL指针指向当前节点FAIL指针指向相应字符接的节点
            {
                FAIL[nxt[now][i]]=nxt[FAIL[now]][i];
                que.push(nxt[now][i]); //加入队列继续遍历
            }
        }
    }
}

int query(char buf[],int l)
{
    int now=root;
    int res=0;
    for(int i=0;i<l;i++)
    {
        now=nxt[now][buf[i]-'a'];
        int temp=now;
        while(temp!=root&&mark[temp]==0)//根据题目要求改变形式
        {
            res+=edd[temp];
            edd[temp]=0;
            mark[temp]=1;
            temp=FAIL[temp];
        }
    }
    return res; //在这里返回的是匹配到的模式串的数量
}

char buf[maxn],ans[maxn];
string A[maxn];

int main()
{
    int T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d",&n);
        init();
        int ma=0;
        for(int i=0;i<n;i++)
        {
            scanf("%s",buf);
            int l=strlen(buf);
            if(ma<l)
            {
                ma=l;
                strcpy(ans,buf);
            }
            insert(buf,l);
        }
        build();
        int sum = query(ans,ma);
        if(sum == n) printf("%s
", ans);
        else puts("No");
    }
}