Computer Virus on Planet Pandora

3
2
AB
DCB
DACB
3
ABC
CDE
GHI
ABCCDEFIHG
4
ABB
ACDEE
BBB
FEEE
A[2B]CD[4E]F

0
3
2
Hint
In the second case in the sample input, the reverse of the program is ‘GHIFEDCCBA’, and ‘GHI’ is a substring of the reverse, so the program is infected 
by virus ‘GHI’.
 

AC自动机水题

/*************************************************************************
    > File Name: hdu3695.cpp
    > Author: ALex
    > Mail: zchao1995@gmail.com 
    > Created Time: 2015年02月04日 星期三 21时17分18秒
 ************************************************************************/

#include <map>
#include <set>
#include <queue>
#include <stack>
#include <vector>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

const double pi = acos(-1);
const int inf = 0x3f3f3f3f;
const double eps = 1e-15;
typedef long long LL;
typedef pair <int, int> PLL;
const int N = 5110000;
char str[1010];
char buf[N];
char input[N];

struct node
{
		node *next[26]; //根据题目而定
		node *fail;
		int count;
		node ()
		{
			fail = NULL;
			for (int i = 0; i < 26; ++i)
			{
				next[i] = NULL;
			}
			count = 0;
		}
};

node *qu[500010];

class AC_Automation
{
	private:
		node *root;
		int head;
		int tail;
	public:
		AC_Automation()
		{
			head = 0;
			tail = 0;
			root = new node();
		}

		void Build_Trie(char str[])
		{
			int len = strlen (str);
			node *p = root;
			for (int i = 0; i < len; ++i)
			{
				int ind = str[i] - 'A';
				if (p -> next[ind] == NULL)
				{
					p -> next[ind] = new node();
				}
				p = p -> next[ind];
			}
			++p -> count;
		}

		void Build_AC ()
		{
			root -> fail = NULL;
			qu[tail++] = root;
			while (head < tail)
			{
				node *now = qu[head++];
				node *p = NULL;
				for (int i = 0; i < 26; ++i)
				{
					if (now -> next[i] != NULL)
					{
						if (now == root)
						{
							now -> next[i] -> fail = root;
						}
						else
						{
							p = now -> fail;
							while (p != NULL)
							{
								if (p -> next[i] != NULL)
								{
									now -> next[i] -> fail = p -> next[i];
									break;
								}
								else
								{
									p = p -> fail;
								}
							}
						}
						if (p == NULL)
						{
							now -> next[i] -> fail = root;
						}
						qu[tail++] = now -> next[i];
					}
				}
			}
		}

		int Match (char buf[])
		{
			int ans = 0;
			int len = strlen (buf);
			node *p = root;
			for (int i = 0; i < len; ++i)
			{
				int ind = buf[i] - 'A';
				while (p -> next[ind] == NULL && p != root)
				{
					p = p -> fail;
				}
				p = p -> next[ind];
				if (p == NULL)
				{
					p = root;
				}
				node *tmp = p;
				while (tmp != root && tmp -> count != -1)
				{
					ans += tmp -> count;
					tmp -> count = -1;
					tmp = tmp -> fail;
				}
			}
			return ans;
		}
		
		void dfs (node *p)
		{
			for (int i = 0; i < 26; ++i)
			{
				if (p -> next[i] != NULL)
				{
					dfs (p -> next[i]);
				}
			}
			delete p;
		}

		~AC_Automation()
		{
			dfs (root);
		}
};

int main ()
{
	int t;
	scanf("%d", &t);
	while (t--)
	{
		int n;
		scanf("%d", &n);
		AC_Automation AC;
		for (int i = 1; i <= n; ++i)
		{
			scanf("%s", str);
			AC.Build_Trie (str);
		}
		scanf("%s", input);
		int len = strlen (input);
		int cnt = 0;
		for (int i = 0; i < len; ++i)
		{
			if (input[i] >= 'A' && input[i] <= 'Z')
			{
				buf[cnt++] = input[i];
			}
			else if (input[i] == '[')
			{
				int x = 0;
				++i;
				while (input[i] >= '0' && input[i] <= '9' && i < len)
				{
					x = x * 10 + input[i++] - '0';
				}
				for (int j = 0; j < x; ++j)
				{
					buf[cnt++] = input[i];
				}
				++i;
			}
			else if (input[i] == ']')
			{
				continue;
			}
		}
		buf[cnt] = '\0';
		AC.Build_AC();
		int ans = AC.Match(buf);
		for (int i = 0;i < cnt / 2; ++i)
		{
			swap (buf[i], buf[cnt - i - 1]);
		}
		ans += AC.Match(buf);
		printf("%d\n", ans);
	}
	return 0;
}

HDU3695---Computer Virus on Planet Pandora

原文：http://blog.csdn.net/guard_mine/article/details/43494477