AC自动机模板
例题 hdu 6208 http://acm.hdu.edu.cn/showproblem.php?pid=6208
1 const int maxn = 1e5; 2 class ac_auto { 3 private: 4 struct node { 5 int ctr; 6 node *fail; 7 node *next[26]; 8 }; 9 node nodes[maxn]; 10 int top; 11 node *root; 12 public: 13 ac_auto() { 14 init(); 15 } 16 inline void init() { 17 top = 0; 18 root = new_node(); 19 } 20 inline node *new_node() { 21 nodes[top].fail = root; 22 nodes[top].ctr = 0; 23 for (int i = 0; i < 26; ++i) 24 nodes[top].next[i] = root; 25 ++top; 26 return &nodes[top - 1]; 27 } 28 void insert(const char *str) { 29 node *head = root; 30 for (; *str; ++str) { 31 int x = *str - 'a'; 32 if (root == head->next[x]) 33 head->next[x] = new_node(); 34 head = head->next[x]; 35 } 36 ++head->ctr; 37 } 38 void build_fail() { 39 queue<node *> q; 40 for (int i = 0; i < 26; ++i) 41 if (root != root->next[i]) 42 q.push(root->next[i]); 43 while (!q.empty()) { 44 node *now = q.front(); 45 q.pop(); 46 for (int i = 0; i < 26; ++i) { 47 if (root == now->next[i]) { 48 now->next[i] = now->fail->next[i]; 49 } else { 50 now->next[i]->fail = now->fail->next[i]; 51 q.push(now->next[i]); 52 } 53 } 54 } 55 } 56 int query(const char *str) { 57 build_fail(); 58 node *head = root; 59 int ret = 0; 60 for (; *str; ++str) { 61 int x = *str - 'a'; 62 head = head->next[x]; 63 node *tmp = head; 64 while (tmp != root) { 65 if (-1 == tmp->ctr) 66 break; 67 ret += tmp->ctr; 68 tmp->ctr = -1; 69 tmp = tmp->fail; 70 } 71 } 72 return ret; 73 } 74 };
