字典树 sdut acm 1500 Message Flood

http://acm.sdut.edu.cn/sdutoj/showproblem.php?pid=1500&cid=1147

#include<stdio.h>
#include<string.h>
#include <stdlib.h>

struct node
{
    int flag;
    struct node * next[26];
};

struct node * newnode()
{
    int i;
    struct node * p =(struct node * )malloc(sizeof(struct node));
                              p->flag = 0;
                              for(i = 0; i < 26; i++)
                              p->next[i] = NULL;
                              return p;
}

void insert(struct node * root, char *s)
{
    struct node * p = root;
    int i, len = strlen(s), t;
    for(i = 0; i < len; i++)
    {
        if(s[i]>='A' && s[i] <= 'Z') t = s[i] -'A';
        else t = s[i] - 'a';
        if(p->next[t] == NULL)
            p->next[t] = newnode();
        p = p->next[t];
    }
    p->flag = 1;
}

int search(struct node * root, char *s)
{
    struct node * p = root;
    int i, t, len = strlen(s);
    for(i = 0; i < len; i++)
    {
        if(s[i]>='A' && s[i] <= 'Z') t = s[i] -'A';
        else t = s[i] - 'a';
        if(p->next[t] == NULL)
            return 0;
        p = p->next[t];
    }
    if(p->flag)
        {p->flag = 0; return 1;}
    return 0;
}

void ReleaseTrie(struct node *T){
    int i;
    for(i=0; i<26; i++){
        if(T->next[i]) ReleaseTrie(T->next[i]);
        T->next[i] = NULL;
    }
    free(T);
}

int main()
{
    int n,m,t,i;
    char s[20];
    while(scanf("%d",&n)!=EOF&&n!=0)
    {
        struct node *root=NULL;
        root=newnode();
        scanf("%d",&m);
        for(i=1;i<=n;i++)
        {
            scanf("%s",s);
            insert(root,s);
        }
        while(m--)
        {
            scanf("%s",s);
            t=search(root,s);
            if(t==1)
            n--;
        }
        printf("%d\n",n);
        ReleaseTrie(root);
    }
    return 0;
}