AC自动机 ( 动态建树模板 )——Keywords Search ( HDU 2222 )

const int k = 26;
const int MAXN = 500100;
struct Node
{
Node* ch[k], *fail;
int match;
void clear()
{
memset(this, 0, sizeof(Node));
}
};
Node * que[MAXN];
struct ACAutomaton
{
Node nodes[MAXN],  *root,  *superRoot, *cur; //全局变量
Node * newNode()  //从内存池中初始化一个结点
{
cur -> clear();
return cur++;
}
void clear()  //清空整个字典树
{
cur = nodes;
superRoot = newNode();
root = newNode();
root -> fail = superRoot;
for(int i=0;i<k;i++)      //superRoot为虚拟的超级根结点，所有孩子均指向实际的根结点，减少建立自动机的代码量
superRoot -> ch[i] = root;
superRoot->match = -1;
}
void insert(char *s)//插入每一个字符，match++
{
Node * t = root;
for(;*s;s++)
{
int x = *s - 'a';
if(t -> ch[x] == NULL)
t -> ch[x] = newNode();
t = t -> ch[x];
}
t -> match++;
}
void build()            //使用自动机前，要先生成失配指针
{
int p=0, q =0;
que[q++] = root;
while(p!=q)         //BFS求失配指针【非常关键的一步，可以好好理解】
{
Node*t = que[p++];
for(int i=0;i<k;i++)
{
if(t->ch[i])
{
t -> ch[i] -> fail = t->fail ->ch[i];
que[q++] = t->ch[i];
}else
t->ch[i] = t -> fail ->ch[i];

}
}
}

int run(char *s)            //计算s中模式串出现的次数
{
int ans = 0;
Node * t = root;
for(; *s ; s++)
{
int x = *s - 'a';
t = t->ch[x];       //记住 t 每次迭代的值！！！便于理解
for(Node*u = t; u->match != -1;u = u->fail)
{
ans += u ->match;
u -> match = -1;   //避免重复计算
}
}
return ans;
}

};

#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <cctype>
#include <map>
#include <set>
#include <queue>
using namespace std;
typedef pair<int,int> Pii;
typedef long long LL;
typedef unsigned long long ULL;
typedef double DBL;
typedef long double LDBL;
#define MST(a,b) memset(a,b,sizeof(a))
#define CLR(a) MST(a,0)
#define Sqr(a) ((a)*(a))

const int k = 26;
const int MAXN = 500100;
struct Node
{
Node* ch[k], *fail;
int match;
void clear()
{
memset(this, 0, sizeof(Node));
}
};
Node * que[MAXN];
struct ACAutomaton
{
Node nodes[MAXN],  *root,  *superRoot, *cur; //全局变量
Node * newNode()  //从内存池中初始化一个结点
{
cur -> clear();
return cur++;
}
void clear()  //清空整个字典树
{
cur = nodes;
superRoot = newNode();
root = newNode();
root -> fail = superRoot;
for(int i=0;i<k;i++)      //superRoot为虚拟的超级根结点，所有孩子均指向实际的根结点，减少建立自动机的代码量
superRoot -> ch[i] = root;
superRoot->match = -1;
}
void insert(char *s)
{
Node * t = root;
for(;*s;s++)
{
int x = *s - 'a';
if(t -> ch[x] == NULL)
t -> ch[x] = newNode();
t = t -> ch[x];
}
t -> match++;
}
void build()            //使用自动机前，要先生成失配指针
{
int p=0, q =0;
que[q++] = root;
while(p!=q)         //BFS求失配指针
{
Node*t = que[p++];
for(int i=0;i<k;i++)
{
if(t->ch[i])
{
t -> ch[i] -> fail = t->fail ->ch[i];
que[q++] = t->ch[i];
}else
t->ch[i] = t -> fail ->ch[i];

}
}
}

int run(char *s)            //在自动机上与匹配串s进行匹配
{
int ans = 0;
Node * t = root;
for(; *s ; s++)
{
int x = *s - 'a';
t = t->ch[x];
for(Node*u = t; u->match != -1;u = u->fail)
{
ans += u ->match;
u -> match = -1;
}
}
return ans;
}

};

int n;
ACAutomaton j;
char s[1000100];
int main()
{
int T;
scanf("%d", &T);
while(T--)
{
scanf("%d", &n);
j.clear();
while(n--)
{
scanf("%s", s);
j.insert(s);
}
j.build();
scanf("%s", s);
printf("%d\n", j.run(s));

}

return 0;
}