多模式字符串匹配算法AC自动机
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1 #include<stdio.h>
2 #include<stdlib.h>
3 #include<ctype.h>
4
5 struct node{
6 node *child[26];
7 node *fail;
8 int flag;
9 };
10 node *create_node()
11 {
12 int*p = (int*)(malloc(sizeof(node)));
13 if(p != NULL){
14 for(int i =0, j =sizeof(node) /sizeof(int); i < j; ++i)
15 p[i] =0;
16 return (node *)p;
17 }
18 else
19 exit(-1);
20 }
21
22 char*modes[10] = {"Word","shi","worship","or","oral",
23 "ship","hiphop","Hop","hip","sword"};
24
25 node *build_trie(char*modes[], int n)
26 {
27 node * root = create_node();
28 for(int i =0; i < n; ++i){
29 node * temp = root;
30 for(int j =0, c = (modes[i])[j]; c !='\0'; ++j, c = (modes[i])[j]){
31 if(c >='A'&& c <='Z') /* convert all uppercases to lowercases */
32 c+=32;
33 int index = c -'a';
34 if(temp->child[index] == NULL)
35 temp->child[index] = create_node();
36 temp = temp->child[index];
37 }
38 temp->flag =1; /* this moment, we reach the end of a word, so set flag 1 */
39 }
40 return root;
41 }
42
43 void BSF(node *root) /* breadth-first search */
44 {
45 if(root == NULL)
46 return;
47 node *queue[100];
48 int head =0;
49 int tail =0;
50 node *temp = root;
51 queue[tail++%100] = temp;
52 printf("R");
53 while(head%100!= tail%100){
54 temp = queue[head%100];
55 for(int i =0; i <26; ++i){
56 if(temp->child[i] != NULL){
57 queue[tail++%100] = temp->child[i];
58 printf(" %c",i +'a');
59 }
60 }
61 ++head;
62 }
63 printf("\n");
64 }
65
66 void DFS(node *root) /* depth-first search */
67 {
68 if(root == NULL)
69 return;
70 node *stack[20];
71 int childs[20];
72 int top =-1;
73 stack[++top] = root;
74 childs[top] ='R';
75 while(top !=-1){
76 node *temp = stack[top];
77 printf("%c ",childs[top]);
78 --top;
79 for(int i =25; i >=0; --i){
80 if(temp->child[i] != NULL){
81 stack[++top] = temp->child[i];
82 childs[top] = i +'a';
83 }
84 }
85 }
86 putchar('\n');
87 }
88
89 void build_automation(node *root) /* build AC_automation(add fail pointer for every node) */
90 {
91 if(root == NULL)
92 return;
93 node *queue[100];
94 int head =0;
95 int tail =0;
96 root->fail = NULL; /* root's fail pointer is NULL*/
97 queue[tail++%100] = root;
98 while(head%100!= tail%100){
99 node *temp = queue[head];
100 for(int i =0; i <26; ++i){
101 if(temp->child[i] != NULL){
102 node *p = temp->fail;
103 while(p != NULL){ /* go on search, until p is NULL or found child[i]'s fail pointer */
104 if(p->child[i] != NULL){ /* p also has child[i]? */
105 temp->child[i]->fail = p->child[i];
106 break;
107 }
108 p = p->fail; /* if p has not child[i], go on search */
109 }
110 if(p == NULL)
111 temp->child[i]->fail = root;
112 queue[tail++%100] = temp->child[i]; /* push child[i] into queue */
113 }
114 }
115 ++head; /* pop temp */
116 }
117 }
118
119 void AC(node *root, FILE *file) /* imaging the file has only letter characters, and has no '\n'*/
120 {
121 int c;
122 node *temp = root;
123 while((c = fgetc(file)) != EOF){
124 c = tolower(c);
125 while(temp != NULL && c != EOF){
126 int i = c -'a';
127 if(temp->child[i] != NULL){
128 if(temp->child[i]->flag){
129 printf("Match\n");
130 }
131 temp = temp->child[i];
132 c = fgetc(file);
133 c = tolower(c);
134 }
135 else {
136 temp = temp->fail;
137 if(temp && temp->flag)
138 printf("Match\n");
139 }
140 }
141 if(temp == NULL)
142 temp = root; /* not match, make temp root to research */
143 }
144 }
145 void main(int argc, char*argv[])
146 {
147 node *root = build_trie(modes, 10);
148 BSF(root);
149 DFS(root);
150 build_automation(root);
151 FILE *file = fopen("tt.txt","r");
152 AC(root, file);
153 }
2 #include<stdlib.h>
3 #include<ctype.h>
4
5 struct node{
6 node *child[26];
7 node *fail;
8 int flag;
9 };
10 node *create_node()
11 {
12 int*p = (int*)(malloc(sizeof(node)));
13 if(p != NULL){
14 for(int i =0, j =sizeof(node) /sizeof(int); i < j; ++i)
15 p[i] =0;
16 return (node *)p;
17 }
18 else
19 exit(-1);
20 }
21
22 char*modes[10] = {"Word","shi","worship","or","oral",
23 "ship","hiphop","Hop","hip","sword"};
24
25 node *build_trie(char*modes[], int n)
26 {
27 node * root = create_node();
28 for(int i =0; i < n; ++i){
29 node * temp = root;
30 for(int j =0, c = (modes[i])[j]; c !='\0'; ++j, c = (modes[i])[j]){
31 if(c >='A'&& c <='Z') /* convert all uppercases to lowercases */
32 c+=32;
33 int index = c -'a';
34 if(temp->child[index] == NULL)
35 temp->child[index] = create_node();
36 temp = temp->child[index];
37 }
38 temp->flag =1; /* this moment, we reach the end of a word, so set flag 1 */
39 }
40 return root;
41 }
42
43 void BSF(node *root) /* breadth-first search */
44 {
45 if(root == NULL)
46 return;
47 node *queue[100];
48 int head =0;
49 int tail =0;
50 node *temp = root;
51 queue[tail++%100] = temp;
52 printf("R");
53 while(head%100!= tail%100){
54 temp = queue[head%100];
55 for(int i =0; i <26; ++i){
56 if(temp->child[i] != NULL){
57 queue[tail++%100] = temp->child[i];
58 printf(" %c",i +'a');
59 }
60 }
61 ++head;
62 }
63 printf("\n");
64 }
65
66 void DFS(node *root) /* depth-first search */
67 {
68 if(root == NULL)
69 return;
70 node *stack[20];
71 int childs[20];
72 int top =-1;
73 stack[++top] = root;
74 childs[top] ='R';
75 while(top !=-1){
76 node *temp = stack[top];
77 printf("%c ",childs[top]);
78 --top;
79 for(int i =25; i >=0; --i){
80 if(temp->child[i] != NULL){
81 stack[++top] = temp->child[i];
82 childs[top] = i +'a';
83 }
84 }
85 }
86 putchar('\n');
87 }
88
89 void build_automation(node *root) /* build AC_automation(add fail pointer for every node) */
90 {
91 if(root == NULL)
92 return;
93 node *queue[100];
94 int head =0;
95 int tail =0;
96 root->fail = NULL; /* root's fail pointer is NULL*/
97 queue[tail++%100] = root;
98 while(head%100!= tail%100){
99 node *temp = queue[head];
100 for(int i =0; i <26; ++i){
101 if(temp->child[i] != NULL){
102 node *p = temp->fail;
103 while(p != NULL){ /* go on search, until p is NULL or found child[i]'s fail pointer */
104 if(p->child[i] != NULL){ /* p also has child[i]? */
105 temp->child[i]->fail = p->child[i];
106 break;
107 }
108 p = p->fail; /* if p has not child[i], go on search */
109 }
110 if(p == NULL)
111 temp->child[i]->fail = root;
112 queue[tail++%100] = temp->child[i]; /* push child[i] into queue */
113 }
114 }
115 ++head; /* pop temp */
116 }
117 }
118
119 void AC(node *root, FILE *file) /* imaging the file has only letter characters, and has no '\n'*/
120 {
121 int c;
122 node *temp = root;
123 while((c = fgetc(file)) != EOF){
124 c = tolower(c);
125 while(temp != NULL && c != EOF){
126 int i = c -'a';
127 if(temp->child[i] != NULL){
128 if(temp->child[i]->flag){
129 printf("Match\n");
130 }
131 temp = temp->child[i];
132 c = fgetc(file);
133 c = tolower(c);
134 }
135 else {
136 temp = temp->fail;
137 if(temp && temp->flag)
138 printf("Match\n");
139 }
140 }
141 if(temp == NULL)
142 temp = root; /* not match, make temp root to research */
143 }
144 }
145 void main(int argc, char*argv[])
146 {
147 node *root = build_trie(modes, 10);
148 BSF(root);
149 DFS(root);
150 build_automation(root);
151 FILE *file = fopen("tt.txt","r");
152 AC(root, file);
153 }
（文件tt.txt只能在第一行上写内容，不能有换行符，而且内容只能是大小写字母）
build_trie:建立字典树。
BSF：广度遍历，输出 R h o s w i o r h w o p p a i o o r h l p p r d l s o d d h p i p
DSF：深度遍历，输出 R h i p h o p o p o r a l s h i p o p w o r d w o r d l d s h i p
验证字典树建立正确；
bulid_automation：在字典树上建立AC自动机的失败指针
AC：AC自动机匹配。
注：任意两个字符串A，B。则A，B有四种关系（A，B可以角色互换）：
①B不是完全包含于A；
②B是A的前缀;
③B是A的后缀;
④B是A的中间一部分，如A=“***B***”;
当A和B同时出现在模式集合中时，且待检测的串中有A：
在①，②,③情况下，AC算法能明确匹配出来,有所响应（可能是输出提示）；
在④情况下，AC算法不能明确提示，但是可以在外部判断，显然如果A匹配则B必定匹配；
有一种属于①②③，A="ship",B="hiphop",c="hip",D="hop"，如果ABCD都在模式集合中，
这种情况ABCD都能检测出来。
还有一种情况属于①②③④，A="shipx",B="hipxhop",c="hip",D="hop",E="x";
这种情况这能检测出ABCD，E不能明确检测出来，可以做外部判断。
