HDU-2222 Keywords Search （AC自动机模板）

题目链接：https://vjudge.net/problem/HDU-2222

#include<bits/stdc++.h> //万能头文件，POJ不支持，其他大部分OJ都支持
using namespace std;
const int maxn = 1e7 + 5;
const int MAX = 10000000;
int cnt;
struct node{
node *next[26];
node *fail;
int sum;
};
node *root;
char key[70];
node *q[MAX];
int head,tail;
node *newnode;
char pattern[maxn];
int N;
void Insert(char *s) //构造字典树
{
node *p = root;
for(int i = 0; s[i]; i++)
{
int x = s[i] - 'a';
if(p->next[x] == NULL)
{
newnode=(struct node *)malloc(sizeof(struct node));
for(int j=0;j<26;j++) newnode->next[j] = 0;
newnode->sum = 0;newnode->fail = 0;
p->next[x]=newnode;
}
p = p->next[x];
}
p->sum++;
}
void build_fail_pointer() //匹配失陪指针fail，相当于KMP的next[]
{
head = 0;
tail = 1;
q[head] = root;
node *p;
node *temp;
while(head < tail)
{
temp = q[head++];
for(int i = 0; i <= 25; i++)
{
if(temp->next[i])
{
if(temp == root)
{
temp->next[i]->fail = root;
}
else
{
p = temp->fail;
while(p)
{
if(p->next[i])
{
temp->next[i]->fail = p->next[i];
break;
}
p = p->fail; //递归查找，类似KMP的思想
}
if(p == NULL) temp->next[i]->fail = root;
}
q[tail++] = temp->next[i];
}
}
}
}
void ac_automation(char *ch)
{
node *p = root;
int len = strlen(ch);
for(int i = 0; i < len; i++)
{
int x = ch[i] - 'a';
while(!p->next[x] && p != root) p = p->fail;
p = p->next[x];
if(!p) p = root;
node *temp = p;
while(temp != root)
{
if(temp->sum >= 0)
{
cnt += temp->sum;
temp->sum = -1;
}
else break;
temp = temp->fail; //递归加入所有的后缀匹配
}
}
}
int main()
{
int T;
scanf("%d",&T);
while(T--)
{
root=(struct node *)malloc(sizeof(struct node));
for(int j=0;j<26;j++) root->next[j] = 0;
root->fail = 0;
root->sum = 0;
scanf("%d",&N);
getchar();
for(int i = 1; i <= N; i++)
{
gets(key);
Insert(key);
}
gets(pattern);
cnt = 0;
build_fail_pointer();
ac_automation(pattern);
printf("%d\n",cnt);
}
return 0;
}