本篇博客是看着kuangbin大神的题写的

1.HDU 2222 Keywords Search

• 题意：求目标串中出现了几个模式串

  #include <bits/stdc++.h>
  using namespace std;
  #define ll long long
  struct Trie
  {
    int next[500010][26],fail[500010],end[500010];
    int root,L;
    int newnode()
    {
        for(int i = 0;i < 26;i++)
            next[L][i] = -1;
        end[L++] = 0;
        return L-1;
    }
    void init()
    {
        L = 0;
        root = newnode();
    }
    void insert(char buf[])
    {
        int len = strlen(buf);
        int now = root;
        for(int i = 0;i < len;i++)
        {
            if(next[now][buf[i]-'a'] == -1)
                next[now][buf[i]-'a'] = newnode();
            now = next[now][buf[i]-'a'];
        }
        end[now]++;
    }
    void build()
    {
        queue<int>Q;
        fail[root] = root;
        for(int i = 0;i < 26;i++)
            if(next[root][i] == -1)
                next[root][i] = root;
            else
            {
                fail[next[root][i]] = root;
                Q.push(next[root][i]);
            }
        while( !Q.empty() )
        {
            int now = Q.front();
            Q.pop();
            for(int i = 0;i < 26;i++)
                if(next[now][i] == -1)
                    next[now][i] = next[fail[now]][i];
                else
                {
                    fail[next[now][i]]=next[fail[now]][i];
                    Q.push(next[now][i]);
                }
        }
    }
    int query(char buf[])
    {
        int len = strlen(buf);
        int now = root;
        int res = 0;
        for(int i = 0;i < len;i++)
        {
            now = next[now][buf[i]-'a'];
            int temp = now;
            while( temp != root )
            {
                res += end[temp];
                end[temp] = 0;
                temp = fail[temp];
            }
        }
        return res;
    }
    void debug()
    {
        for(int i = 0;i < L;i++)
        {
            printf("id = %3d,fail = %3d,end = %3d,chi = [",i,fail[i],end[i]);
            for(int j = 0;j < 26;j++)
                printf("%2d",next[i][j]);
            printf("]\n");
        }
    }
  };
  char buf[1000010];
  Trie ac;
  int main()
  {
    int T;
    int n;
    scanf("%d",&T);
    while( T-- )
    {
        scanf("%d",&n);
        ac.init();
        for(int i = 0;i < n;i++)
        {
            scanf("%s",buf);
            ac.insert(buf);
        }
        ac.build();
        scanf("%s",buf);
        printf("%d\n",ac.query(buf));
    }
    return 0;
  }

2.HDU 2896 病毒侵袭

• 题意：和上一题差不多，要求输出模式串的下标

  #include <bits/stdc++.h>
  using namespace std;
  #define ll long long
  struct Trie
  {
    int next[210*500][128],fail[210*500],end[210*500];
    int root,L;
    int newnode()
    {
        for(int i = 0;i < 128;i++)
            next[L][i] = -1;
        end[L++] = -1;
        return L-1;
    }
    void init()
    {
        L = 0;
        root = newnode();
    }
    void insert(char s[],int id)
    {
        int len = strlen(s);
        int now = root;
        for(int i = 0;i < len;i++)
        {
            if(next[now][s[i]] == -1)
                next[now][s[i]] = newnode();
            now=next[now][s[i]];
        }
        end[now]=id;
    }
    void build()
    {
        queue<int>Q;
        fail[root] = root;
        for(int i = 0;i < 128;i++)
            if(next[root][i] == -1)
                next[root][i] = root;
            else
            {
                fail[next[root][i]] = root;
                Q.push(next[root][i]);
            }
        while(!Q.empty())
        {
            int now = Q.front();
            Q.pop();
            for(int i = 0;i < 128;i++)
                if(next[now][i] == -1)
                    next[now][i] = next[fail[now]][i];
                else
                {
                    fail[next[now][i]] = next[fail[now]][i];
                    Q.push(next[now][i]);
                }
        }
    }
    bool used[510];
    bool query(char buf[],int n,int id)
    {
        int len = strlen(buf);
        int now = root;
        memset(used,false,sizeof(used));
        bool flag = false;
        for(int i = 0;i < len;i++)
        {
            now = next[now][buf[i]];
            int temp = now;
            while(temp != root)
            {
                if(end[temp] != -1)
                {
                    used[end[temp]] = true;
                    flag = true;
                }
                temp = fail[temp];
            }
        }
        if(!flag)return false;
        printf("web %d:",id);
        for(int i = 1;i <= n;i++)
            if(used[i])
                printf(" %d",i);
        printf("\n");
        return true;
    }
  };
  char buf[10010];
  Trie ac;
  int main()
  {
    int n,m;
    while(scanf("%d",&n) != EOF)
    {
        ac.init();
        for(int i = 1;i <= n;i++)
        {
            scanf("%s",buf);
            ac.insert(buf,i);
        }
        ac.build();
        int ans = 0;
        scanf("%d",&m);
        for(int i = 1;i <= m;i++)
        {
            scanf("%s",buf);
            if(ac.query(buf,n,i))
                ans++;
        }
        printf("total: %d\n",ans);
    }
    return 0;
  }

  3.HDU 3065 病毒侵袭持续中

题意：还是差不多，就是需要输出每个模式串出现的次数

#include <bits/stdc++.h>
using namespace std;
#define ll long long
char str[1010][100];
struct Trie
{
    int next[1010*50][128],fail[1010*50],end[1010*50];
    int root,L;
    int newnode()
    {
        for(int i = 0;i < 128;i++)
            next[L][i] = -1;
        end[L++] = -1;
        return L-1;
    }
    void init()
    {
        L = 0;
        root = newnode();
    }
    void insert(char s[],int id)
    {
        int len = strlen(s);
        int now = root;
        for(int i = 0;i < len;i++)
        {
            if(next[now][s[i]] == -1)
                next[now][s[i]] = newnode();
            now = next[now][s[i]];
        }
        end[now] = id;
    }
    void build()
    {
        queue<int>Q;
        fail[root] = root;
        for(int i = 0;i < 128;i++)
            if(next[root][i] == -1)
                next[root][i] = root;
            else
            {
                fail[next[root][i]] = root;
                Q.push(next[root][i]);
            }
        while(!Q.empty())
        {
            int now = Q.front();
            Q.pop();
            for(int i = 0;i < 128;i++)
                if(next[now][i] == -1)
                    next[now][i]=next[fail[now]][i];
                else
                {
                    fail[next[now][i]]=next[fail[now]][i];
                    Q.push(next[now][i]);
                }
        }
    }
    int num[1010];
    void query(char buf[],int n)
    {
        for(int i = 0;i < n;i++)
            num[i] = 0;
        int len=strlen(buf);
        int now=root;
        for(int i=0;i<len;i++)
        {
            now=next[now][buf[i]];
            int temp = now;
            while( temp != root )
            {
                if(end[temp] != -1)
                    num[end[temp]]++;
                temp = fail[temp];
            }
        }
        for(int i = 0;i < n;i++)
            if(num[i] > 0)
                printf("%s: %d\n",str[i],num[i]);
    }

};

char buf[2000010];
Trie ac;
void debug()
{
    for (int i = 0; i < ac.L; i++)
    {
        printf("id = %3d ,fail = %3d ,end = %3d, chi = [",i,ac.fail[i],ac.end[i]);
        for (int j = 0; j < 128; j++)
            printf("%2d ",ac.next[i][j]);
        printf("]\n");
    }
}
int main()
{
    int n;
    while(scanf("%d",&n) == 1)
    {
        ac.init();
        for(int i = 0;i < n;i++)
        {
            scanf("%s",str[i]);
            ac.insert(str[i],i);
        }
        ac.build();
        scanf("%s",buf);
        ac.query(buf,n);
    }
    return 0;
}