hdu 1251 统计难题（字典树）

#include <cstdio>
#include <cstring>

struct trie
{
trie *next[26]; // 假设只有26个小写字母
int ch;         // 统计有多少个单词覆盖到当前结点
trie() {        // 用于初始化的构造函数
memset(next, 0, sizeof(next));
ch = 1;
}
} *root;

void insert(char *s)
{
trie *p = root;
while(*s) {
int index = *s - 'a';
if(p->next[index]) p->next[index]->ch++;
else p->next[index] = new trie;
p = p->next[index];
s++;
}
}

int search(char *s)
{
trie *p = root;
while(*s) {
int index = *s - 'a';
if(!p->next[index]) return 0;
p = p->next[index];
s++;
}
return p->ch;
}

int main()
{
root = new trie;
char s[15];
while(gets(s), s[0] != '\0') insert(s);
while(gets(s)) printf("%d\n", search(s));
return 0;
}