Trie树

#include <stdio.h>
#include <malloc.h>

#define MAXN  26

struct Trie{
int count;   //单词计数
int flag;    // 1表示是单词，0表示不是单词
struct Trie *next[MAXN];
};

struct Trie *rt;

//初始化Trie树
void trie_init(){
int i;
rt = (struct Trie*)malloc(sizeof(struct Trie));

rt->count = 0;
rt->flag = 0;
for(i=0; i<MAXN; ++i)
rt->next[i] = NULL;
}

//插入单词
void trie_insert(char *s){
int i;
struct Trie *tmp = rt;

for(s; *s!='\0'; ++s){
if(tmp->next[*s -'a'] == NULL){
struct Trie *cur = (struct Trie*)malloc(sizeof(struct Trie));
cur->count = 0;
cur->flag = 0;
for(i=0; i<MAXN; ++i)
cur->next[i] = NULL;
tmp->next[*s -'a'] = cur;
}
tmp->count++;
tmp = tmp->next[*s -'a'];
}
tmp->flag = 1;
tmp->count++;
}

//查询给定字符串前缀的单词数目
int trie_search(char *s){

struct Trie *tmp = rt;
for(s; *s!='\0'; ++s){
if(tmp->next[*s -'a'] == NULL)
return 0;
tmp = tmp->next[*s -'a'];
}
return tmp->count;
}

//删除整个Trie树
void trie_del(struct Trie *root){
int i;
for(i=0; i<MAXN; ++i){
if(root->next[i] != NULL)
trie_del(root->next[i]);
}
free(root);
}

int main(){
int i, n, m;
char ch[15];

FILE *fin;
fin = fopen("input.txt", "r");

while(fscanf(fin, "%d", &n) != EOF){
trie_init();
for(i=0; i<n; ++i){
fscanf(fin, "%s", ch);
trie_insert(ch);
}
fscanf(fin, "%d", &m);
for(i=0; i<m; ++i){
fscanf(fin, "%s", ch);
printf("%d\n", trie_search(ch));
}
trie_del(rt);
}

return 0;
}