1 #include <iostream>
2 #include <string>
3 using namespace std;
4 #define ALPHABET_SIZE 26
5
6 typedef struct trie_node
7 {
8 int count; // 记录该节点代表的单词的个数
9 trie_node *children[ALPHABET_SIZE]; // 各个子节点
10 }*trie;
11
12 trie_node* create_trie_node()
13 {
14 trie_node* pNode = new trie_node();
15 pNode->count = 0;
16 for(int i=0; i<ALPHABET_SIZE; ++i)
17 pNode->children[i] = NULL;
18 return pNode;
19 }
20
21 void trie_insert(trie root, char* key)
22 {
23 trie_node* node = root;
24 char* p = key;
25 while(*p)
26 {
27 if(node->children[*p-'a'] == NULL)
28 {
29 node->children[*p-'a'] = create_trie_node();
30 }
31 node = node->children[*p-'a'];
32 ++p;
33 }
34 node->count += 1;
35 }
36 /*
37 查询：不存在返回0，存在返回出现的次数
38 */
39 int trie_search(trie root, char* key)
40 {
41 trie_node* node = root;
42 char* p = key;
43 while(*p && node!=NULL)
44 {
45 node = node->children[*p-'a'];
46 ++p;
47 }
48 if(node == NULL)
49 return 0;
50 else
51 return node->count;
52 }
53
54 int main()
55 {
56 // 关键字集合
57 char keys[][8] = {"the", "a", "there", "answer", "any", "by", "bye", "their"};
58 trie root = create_trie_node();
59 // 创建trie树
60 for(int i = 0; i < 8; i++)
61 trie_insert(root, keys[i]);
62 // 检索字符串
63 char s[][32] = {"Present in trie", "Not present in trie"};
64 printf("%s --- %s\n", "the", trie_search(root, "the")>0?s[0]:s[1]);
65 printf("%s --- %s\n", "these", trie_search(root, "these")>0?s[0]:s[1]);
66 printf("%s --- %s\n", "their", trie_search(root, "their")>0?s[0]:s[1]);
67 printf("%s --- %s\n", "thaw", trie_search(root, "thaw")>0?s[0]:s[1]);
68 return 0;
69 }
