标签:des style blog color io os ar java strong
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 35655 Accepted Submission(s): 11496
Mean:
给你n个单词,再给你一篇文章,让你统计有多少个单词在文章中出现过。
analyse:
裸的AC自动机,模板题。
Time complexity:o(n)+o(ml) n个模式串长度均不超过m,文本串长度为L
Source code:
// Memory Time
// 1347K 0MS
// by : Snarl_jsb
// 2014-09-29-20.14
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<map>
#include<string>
#include<climits>
#include<cmath>
#define N 10010
#define LL long long
using namespace std;
namespace ac_auto
{
char str[1000005];
struct node
{
node *next[26];
node *fail;
int count;
node()
{
for(int i = 0; i < 26; i++)
next[i] = NULL;
count = 0;
fail = NULL;
}
}*q[50*N];
node *root;
int head, tail;
void Insert(char *str) // 插入单词
{
node *p = root;
int i = 0, index;
while(str[i]) {
index = str[i] - ‘a‘;
if(p->next[index] == NULL)
p->next[index] = new node();
p = p->next[index];
i++;
}
p->count++;
}
void build_ac_automation(node *root) // bfs建立fail指针
{
root->fail = NULL;
q[tail++] = root;
while(head < tail) {
node *temp = q[head++];
node *p = NULL;
for(int i = 0; i < 26; i++) {
if(temp->next[i] != NULL) {
if(temp == root) temp->next[i]->fail = root;
else {
p = temp->fail;
while(p != NULL) {
if(p->next[i] != NULL) {
temp->next[i]->fail = p->next[i];
break;
}
p = p->fail;
}
if(p == NULL) temp->next[i]->fail = root;
}
q[tail++] = temp->next[i];
}
}
}
}
int Query(node *root) // 匹配 + 统计
{
int i = 0, cnt = 0, index;
node *p = root;
while(str[i]) {
index = str[i] - ‘a‘;
while(p->next[index] == NULL && p != root) p = p->fail;
p = p->next[index];
if(p == NULL) p = root;
node *temp = p;
while(temp != root && temp->count != -1) {
cnt += temp->count;
temp->count = -1;
temp = temp->fail;
}
i++;
}
return cnt;
}
}
using namespace ac_auto;
int main()
{
int T, n;
scanf("%d",&T);
while(T--)
{
head = tail = 0; // 清零
root = new node(); // 申请新的root结点
scanf("%d",&n);
while(n--)
{
scanf("%s", str);
Insert(str); // 插入单词
}
build_ac_automation(root); // 建树
scanf("%s",str);
printf("%d\n", Query(root)); // 查找+统计
}
return 0;
}
AC自动机 - 多模式串匹配问题的基本运用 + 模板题 --- HDU 2222
标签:des style blog color io os ar java strong
原文地址:http://www.cnblogs.com/acmer-jsb/p/4000884.html