我用字典树写的 按照题意做就行

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
class trie
{
public:
    trie* next[26];
    char str_temp[12];
    int num; //记录前缀的个数
    bool value; //标记这里是不是一个单词
    trie()
    {
        for(int i=0; i<26; i++)
        next[i]=0;
        value=0;
        num=0;
    }
} root;
void insert(trie* p,char* s,char* s1)
{
    p=&root;
    int k=0;
    while(s[k]!='\0')
    {
        if(!p->next[s[k]-'a'])
        p->next[s[k]-'a']=new trie;
        p=p->next[s[k]-'a'];
        p->num++;
        k++;
    }
    p->value=1;
    strcpy(p->str_temp,s1);
  //  cout<<p->str_temp<<endl;
}
//查找
int find(trie* p,char* s)
{
    p=&root;
    int k=0;
    while(s[k]!='\0'&&p->next[s[k]-'a'])
    {
        p=p->next[s[k]-'a'];
        k++;
    }
   // cout<<endl<<"test"<<"   "<<k<<"  "<<strlen(s)<<endl;
    if(p->value&&s[k]=='\0')  //我少了s[k]=='\0'这个WA了8次
    {
        printf("%s",p->str_temp);
        return 1;
    }
    return 0;
}

int main()
{
    char str[12],str1[12],cstr[3010],astr[12];
    trie *p=&root;
    while(scanf("%s",str)!=EOF&&strcmp(str,"END")!=0)
    {
        if(!strcmp(str,"START"))
        continue;
        scanf("%s",str1);
        insert(p,str1,str);
    }
    getchar();
    while(gets(cstr)&&strcmp(cstr,"END")!=0)
    {
         if(!strcmp(cstr,"START"))
         continue;
         memset(astr,'\0',sizeof(astr));
         for(int i=0,j=0;cstr[i]!='\0';i++)
            {
                if(cstr[i]<='z'&&cstr[i]>='a')
                {
                    astr[j]=cstr[i];
                    j++;
                }
                else
                {
                    int m=find(p,astr);
                    if(!m)
                    printf("%s",astr);
                    printf("%c",cstr[i]);
                    if(j)
                    {
                        memset(astr,'\0',sizeof(astr));
                        j=0;
                    }
                }
            }
                 printf("\n");
    }
    return 0;
}