hdu1075What Are You Talking About(trie树）

http://acm.hdu.edu.cn/showproblem.php?pid=1075
难得的1A 把对应的英语单词存在火星文字最后一个字母的结构体字符串中挨个找
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  1 #include <iostream>
  2 #include<cstdio>
  3 #include<string.h>
  4 #include<stdlib.h>
  5 using namespace std;
  6 int flag;
  7 struct node
  8 {
  9     int flag;
 10     char s[21];
 11     node *next[27];
 12     node()
 13     {
 14         flag = 0;
 15         memset(next,NULL,sizeof(next));
 16     }
 17 };
 18 void trie(node *head,char *c1,char *c2)
 19 {
 20     int k1 = strlen(c2),i,d;
 21     node *p = head;
 22     for(i =0 ; i < k1 ; i++)
 23     {
 24         d = c2[i]-'a';
 25         if(p->next[d]==NULL)
 26         {
 27             p->next[d] = new node;
 28         }
 29         p = p->next[d];
 30     }
 31 
 32     p->flag = 1;
 33     strcpy(p->s,c1);
 34 }
 35 void search(node *head,char *c)
 36 {
 37     int i,j,k = strlen(c),d;
 38     node *p = head;
 39     for(i = 0 ; i < k ; i++)
 40     {
 41         d = c[i]-'a';
 42         if(p->next[d]==NULL)
 43         {
 44             flag = 0;
 45             return;
 46         }
 47         p=p->next[d];
 48     }
 49     if(p->flag == 1)
 50     {
 51         flag = 1;
 52         printf("%s",p->s);
 53     }
 54 }
 55 int main()
 56 {
 57     int i,j,k,n,g,w;
 58     char c1[20],c2[20],str[3001],s[21];
 59     node *head = new node;
 60     scanf("%s",c1);
 61     while(scanf("%*c%s",c1)!=EOF)
 62     {
 63         if(strcmp(c1,"END")==0)
 64         break;
 65         scanf("%s",c2);
 66         trie(head,c1,c2);
 67     }
 68     scanf("%s",c1);
 69     getchar();
 70     while(gets(str)!=NULL)
 71     {
 72         if(strcmp(str,"END")==0)
 73         break;
 74         k = strlen(str);
 75         int f = 0;
 76         g= 0;
 77         for(i =0 ; i < k ; i++)
 78         {
 79             if(str[i]>='a'&&str[i]<='z')
 80             {
 81                 s[g++] = str[i];
 82                 f = 1;
 83             }
 84             else
 85             {
 86                 if(f)
 87                 {
 88                     f = 0;
 89                     flag = 0;
 90                     s[g]='\0';
 91                     g = 0;
 92                     search(head,s);
 93                     if(!flag)
 94                     printf("%s",s);
 95                     printf("%c",str[i]);
 96                 }
 97                 else
 98                 printf("%c",str[i]);
 99             }
100         }
101         if(str[k-1]>='a'&&str[k-1]<='z')
102         {
103             s[g] = '\0';
104             flag = 0;
105             search(head,s);
106             if(!flag)
107             printf("%s",s);
108         }
109         puts("");
110     }
111     return 0;
112 }