字典树

理解很简单，但是我对指针不太熟悉，明天先把指针再看看，再回来学
学习链接;http://www.cnblogs.com/tanky_woo/archive/2010/09/24/1833717.html
http://www.cnblogs.com/binyue/p/3771040.html
http://blog.csdn.net/jiutianhe/article/details/8076835
http://blog.csdn.net/hihozoo/article/details/51248823
http://www.cnblogs.com/Bob-FD/p/3378379.html

#include<stdio.h>#include <iostream>#include <string>using namespace std;#define ALPHABET_SIZE 26typedef struct trie_node{    int count;   // 记录该节点代表的单词的个数    trie_node *children[ALPHABET_SIZE]; // 各个子节点}*trie;trie_node* create_trie_node(){    trie_node* pNode = new trie_node();    pNode->count = 0;    for(int i=0; i<ALPHABET_SIZE; ++i)        pNode->children[i] = NULL;    return pNode;}void trie_insert(trie root, char* key){    trie_node* node = root;    char* p = key;    while(*p)    {        if(node->children[*p-'a'] == NULL)        {            node->children[*p-'a'] = create_trie_node();        }        node = node->children[*p-'a'];        ++p;    }    node->count += 1;}/** * 查询：不存在返回0，存在返回出现的次数 */int trie_search(trie root, char* key){    trie_node* node = root;    char* p = key;    while(*p && node!=NULL)    {        node = node->children[*p-'a'];        ++p;    }    if(node == NULL)        return 0;    else        return node->count;}int main(){    // 关键字集合    char keys[][8] = {"the", "a", "there", "answer", "any", "by", "bye", "their"};    trie root = create_trie_node();    // 创建trie树    for(int i = 0; i < 8; i++)        trie_insert(root, keys[i]);    // 检索字符串    char s[][32] = {"Present in trie", "Not present in trie"};    printf("%s --- %s\n", "the", trie_search(root, "the")>0?s[0]:s[1]);    printf("%s --- %s\n", "these", trie_search(root, "these")>0?s[0]:s[1]);    printf("%s --- %s\n", "their", trie_search(root, "their")>0?s[0]:s[1]);    printf("%s --- %s\n", "thaw", trie_search(root, "thaw")>0?s[0]:s[1]);    return 0;}