hdu2222(AC自动机）

本题注意模式串匹配不可重复查找

实际上是输出有几种模式串出现在文本串中

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

const int INF = 0x7FFFFFFF;
const int maxn = 26;

char ss[1000000+maxn];

struct Node
{
    Node *next[maxn];
    Node *pre;
    int last;
    Node ()
    {
        memset(next, 0, sizeof (next));
        pre = 0, last = 0;
    }
};

Node *root;

void Init ()
{
    root = new Node;
}

void Insert (char *s)
{
    if (!s[0]) return ;

    Node *p = root;
    for (int i = 0; s[i]; i++)
    {
        if (!p -> next[s[i]-'a'])
            p -> next[s[i]-'a'] = new Node;

        p = p -> next[s[i]-'a'];
    }
    p -> last++;//记录该节点单词总共插入的次数
}

void Build ()
{
    queue <Node*> qu;
    for (int i = 0; i < maxn; i++)
        if (root -> next[i])
        {
            root -> next[i] -> pre = root;
            qu.push (root -> next[i]);
        }

    while (!qu.empty ())
    {
        Node *temp = qu.front (); qu.pop ();
        for (int i = 0; i < maxn; i++)
        {
            Node *pp = temp -> next[i];
            if (pp)
            {
                Node *par = temp -> pre;
                do
                {
                    if (par -> next[i])
                    {
                        pp -> pre = par -> next[i];
                        break;
                    }

                    else
                        par = par -> pre;
                } while (par);

                if (!par)
                    pp -> pre = root;

                qu.push (pp);
            }
        }
    }
}

int Query (char *s)
{
    if (!s[0]) return 0;

    Node *p = root;
    int cnt = 0;
    for (int i = 0; s[i]; i++)
    {
        while (p != root && !p -> next[s[i]-'a'])
            p = p -> pre;

        p = p -> next[s[i]-'a'];
        if (!p)
            p = root;

        Node *pp = p;
        while (pp != root && pp -> last != -1)
        {
            cnt += pp -> last;
		    pp -> last = -1;//不可重复查找
            pp = pp -> pre;
        }
    }
    return cnt;
}

void DelTree (Node *s)
{
    if (!s) return ;

    for (int i = 0; i < maxn; i++)
    {
        if (s -> next[i])
            DelTree (s -> next[i]);
    }
    delete s;
}

int main()
{
    int t;
    scanf ("%d", &t);
    while (t--)
    {
        int n;
        scanf ("%d",&n);
        Init ();

        for (int i = 1; i <= n; i++)
        {
            scanf ("%s", ss);
            Insert (ss);
        }

        getchar();
        gets (ss);

        Build ();

        printf ("%d\n", Query (ss));
        DelTree (root);
    }

return 0;
}

1
2
aa
bb
aacdaacd
1