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P3808 【模板】AC 自动机（简单版）

Browse Source 
https://www.luogu.com.cn/record/98366475
This commit is contained in:
Baoshuo Ren 2022-12-31 17:15:29 +08:00
parent 4cd9aa2cfa
commit 9184137474
Signed by: baoshuo
GPG Key ID: 00CB9680AB29F51A
1 changed files with 17 additions and 43 deletions
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60
Luogu/P3808/P3808.cpp
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@ -1,7 +1,7 @@
#include <iostream> #include <iostream>
#include <memory>
#include <queue> #include <queue>
#include <string> #include <string>
#include <unordered_map>
using std::cin; using std::cin;
using std::cout; using std::cout;
@ -11,38 +11,26 @@ class AcAutomaton {
private: private:
struct node { struct node {
int cnt; int cnt;
node *child[26], *fail; std::shared_ptr<node> child[26], fail;
node() node()
: cnt(0), fail(nullptr) { : cnt(0), fail(nullptr) {
std::fill_n(child, 26, nullptr); std::fill(std::begin(child), std::end(child), nullptr);
}
~node() {
for (int i = 0; i < 26; i++) {
if (child[i] != nullptr) {
delete child[i];
}
}
} }
}; };
node* root; std::shared_ptr<node> root;
public: public:
AcAutomaton() AcAutomaton()
: root(new node()) {} : root(new node()) {}
~AcAutomaton() {
delete root;
}
void insert(std::string s) { void insert(std::string s) {
node* cur = root; std::shared_ptr<node> cur = root;
for (char c : s) { for (char c : s) {
if (cur->child[c - 'a'] == nullptr) { if (cur->child[c - 'a'] == nullptr) {
cur->child[c - 'a'] = new node(); cur->child[c - 'a'] = std::make_shared<node>();
} }
cur = cur->child[c - 'a']; cur = cur->child[c - 'a'];
@ -52,11 +40,11 @@ class AcAutomaton {
} }
void build() { void build() {
std::queue<node*> q; std::queue<std::shared_ptr<node>> q;
for (int i = 0; i < 26; i++) { for (int i = 0; i < 26; i++) {
if (root->child[i] != nullptr) { if (root->child[i] != nullptr) {
q.push(root->child[i]); q.emplace(root->child[i]);
root->child[i]->fail = root; root->child[i]->fail = root;
} }
} }
@ -66,41 +54,27 @@ class AcAutomaton {
q.pop(); q.pop();
for (int i = 0; i < 26; i++) { for (int i = 0; i < 26; i++) {
if (cur->child[i] == nullptr) continue; if (cur->child[i] != nullptr) {
cur->child[i]->fail = cur->fail->child[i] == nullptr ? root : cur->fail->child[i];
auto p = cur->fail; q.emplace(cur->child[i]);
} else {
while (p != nullptr) { cur->child[i] = cur->fail->child[i] == nullptr ? root : cur->fail->child[i];
if (p->child[i] != nullptr) {
cur->child[i]->fail = p->child[i];
break;
}
p = p->fail;
} }
if (p == nullptr) cur->child[i]->fail = root;
q.push(cur->child[i]);
} }
} }
} }
int query(std::string t) { int query(std::string t) {
int res = 0; int res = 0;
node* cur = root; std::shared_ptr<node> cur = root;
for (char c : t) { for (char c : t) {
while (cur != root && cur->child[c - 'a'] == nullptr) cur = cur->fail;
cur = cur->child[c - 'a'] == nullptr ? root : cur->child[c - 'a']; cur = cur->child[c - 'a'] == nullptr ? root : cur->child[c - 'a'];
node* p = cur; for (std::shared_ptr<node> i = cur; i != nullptr && i->cnt != -1; i = i->fail) {
res += i->cnt;
while (p != root && p->cnt >= 0) { i->cnt = -1;
res += p->cnt;
p->cnt = -1;
p = p->fail;
} }
} }