hdu2222 Keywords Search (AC自动机)

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2222

AC自动机板子题

#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<queue>
using namespace std;
typedef long long ll;

const int maxn = 1000010; 

int T, n, rt = 0, tot = 0; 
ll ans = 0;
struct Node{
	int son[30], sz, fail;
}t[maxn];

char s[maxn];

void insert(){
	int p = rt;
	int len = strlen(s);
	for(int i = 0 ; i < len ; ++i){
		if(!t[p].son[s[i] - 'a']){
			t[p].son[s[i] - 'a'] = ++tot;
		}
		p = t[p].son[s[i] - 'a'];
	} 
	++t[p].sz;
}

queue<int> q; 
void build(){
	t[rt].fail = rt;
	for(int i = 0 ; i <= 25 ; ++i){
		if(t[rt].son[i]) q.push(t[rt].son[i]);
	}
	
	while(!q.empty()){
		int u = q.front(); q.pop();
		for(int i = 0 ; i <= 25 ; ++i){
			if(t[u].son[i]){
				t[t[u].son[i]].fail = t[t[u].fail].son[i];
				q.push(t[u].son[i]);
			} else{
				t[u].son[i] = t[t[u].fail].son[i];
			}
		}
	}
}

void query(){
	int p = rt;
	int len = strlen(s);
	for(int i = 0 ; i < len ; ++i){
		p = t[p].son[s[i] - 'a'];
		for(int j = p ; j && ~t[j].sz ; j = t[j].fail) ans += t[j].sz, t[j].sz = -1;
	}
}

ll read(){ ll s = 0, f = 1; char ch = getchar(); while(ch < '0' || ch > '9'){ if(ch == '-') f = -1; ch = getchar(); } while(ch >= '0' && ch <= '9'){ s = s * 10 + ch - '0'; ch = getchar(); } return s * f; }

int main(){
	T = read();
	while(T--){
		memset(t, 0, sizeof(t));
		tot = 0, ans = 0;
		n = read();
		for(int i = 1 ; i <= n ; ++i){
			scanf("%s", s);
			insert();
		}
		
		build();
		
		scanf("%s", s);
		query();
		
		printf("%lld
", ans);
				
	}

	return 0;
}