字典树 HDU 1251 统计难题

http://acm.hdu.edu.cn/showproblem.php?pid=1251

#include<iostream>
#include<algorithm>
#include<stdio.h>
using namespace std;
struct node
{
    int sum;
    node *next[26];
};
void buildtrietree(node *head, char s[])
{
    node *p=new node();
    p=head;
    for(int i=0; s[i]; i++)
    {
        int k=s[i]-‘a‘;
        if(p->next[k]==0)
            p->next[k]=new node();
        p=p->next[k];
        p->sum++;
    }
}

int query(node *head, char s[])
{
    node *p=new node();
    p=head;
    for(int i=0; s[i]; i++)
    {
        int k=s[i]-‘a‘;
        if(p->next[k]==0)
            return 0;
        p=p->next[k];
    }
    return p->sum;
}
int main()
{
    char s[12];
    node *head=new node();
    while(gets(s), s[0])
        buildtrietree(head, s);
    while(cin >> s)
        printf("%d\n", query(head, s));
    return 0;
}