hdu 3065 病毒侵袭持续中 (ac自动机)

题目链接

 

题意：给出n个病毒的模式串，问每个病毒串在文本串中出现了多少次。

思路：ac自动机。模式串只由大写字母组成。文本串是所有可视字符。 如果动态128会MLE.做法是换成静态数组写法，或者对于每次Search的时候，出现非大写字母的字符特判一下。

 

C++
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/* ***********************************************
Author :111qqz
Created Time :2016年08月18日 星期四 00时17分38秒
File Name :code/hdu/3065.cpp
************************************************ */
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <cstdlib>
#include <deque>
#define fst first
#define sec second
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
#define ms(a,x) memset(a,x,sizeof(a))
typedef long long LL;
#define pi pair < int ,int >
#define MP make_pair
using namespace std;
const double eps = 1E-8;
const int dx4[4]={1,0,0,-1};
const int dy4[4]={0,-1,1,0};
const int inf = 0x3f3f3f3f;
const int sizTrie = 26;
map<int,int>mp;
char ill[1005][50];
struct Trie
{
    struct Node
    {
        Node *nxt[sizTrie];
        Node *fail;
        int cnt;
        int id;
        Node()
        {
            for ( int i = 0 ; i < sizTrie; i++) nxt[i]=NULL;
            cnt = 0 ;
            id = 0 ;
            fail = NULL;
        }
    };
    Node *root;
    void init()
    {
        root = new Node();
    }
    void Insert(char *s,int x)
    {
        int len = strlen(s);
        Node *u = root;
        for ( int i = 0 ; i < len ; i++ )
        {
            int v = s[i]-'A';
            if (u->nxt[v]==NULL) u->nxt[v] = new Node();
            u = u->nxt[v];
        }
        u->cnt++;
        u->id = x;
//        cout<<"s:"<<s<<" cnt:"<< u->cnt <<endl;
    }
    void getFail()
    {
        root->fail = root;
        queue<Node*>Q;
        for ( int i = 0 ; i < sizTrie ; i++)
        {
            if (root->nxt[i]==NULL)
                root->nxt[i] = root;
            else
            {
                root->nxt[i]->fail = root;
                Q.push(root->nxt[i]);
            }
        }
        while (!Q.empty())
        {
            Node * cur = Q.front();
            Q.pop();
            for ( int i = 0 ; i < sizTrie ; i++)
            {
                if (cur->nxt[i]==NULL)
                    cur->nxt[i] = cur->fail->nxt[i];
                else
                {
                    cur->nxt[i]->fail = cur->fail->nxt[i];
                    Q.push(cur->nxt[i]);
                }
            }
        }
    }
        void Search(char *s)
        {
            int len = strlen(s);
            Node *u = root;
            mp.clear();
            for ( int i = 0 ; i < len ; i++)
            {
                if (s[i]<'A'||s[i]>'Z')
                {
                    u = root; //不要忘记，出现不可能被匹配的字符，相当于重新初始化了
                    continue;
                }
                int v = s[i]-'A';
                u = u->nxt[v];
                Node * tmp = u;
                while (tmp!=root)
                {
                    if (tmp->id)
                    mp[tmp->id]++;
                    tmp = tmp->fail;
                }
            }
            for (auto it = mp.begin() ; it!=mp.end() ; it++)
//                if (strcmp(ill[it->fst],"")!=0)
                printf("%s: %d\n",ill[it->fst],it->sec);
/*            //sort(ans.begin(),ans.end());
            int siz = ans.size();
            cout<<"anszie:"<<ans.size()<<endl;
            for ( int i = 0 ; i < siz;  i++)
            {
                printf("%s: %d\n",ill[ans[i].fst],ans[i].sec);
            }   */
        }
}ac;
const int N=2E6+7;
int n;
char str[N];
int main()
{
        #ifndef  ONLINE_JUDGE
        freopen("code/in.txt","r",stdin);
  #endif
        while (scanf("%d",&n)!=EOF)
        {  
            ac.init();
            for ( int i = 1 ; i <= n ; i++)
            {
                scanf("%s",ill[i]);
                ac.Insert(ill[i],i);
            }
            ac.getFail();
            scanf("%s",str);
            //        cout<<"str:"<<str<<endl;
            ac.Search(str);
        }
  #ifndef ONLINE_JUDGE  
  fclose(stdin);
  #endif
    return 0;
}
 
 
 
 

 

 

 

作者： CrazyKK

ex-ACMer@hust，stackoverflow-engineer@sensetime

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