trie树

 

#include <stdio.h>
#include <iostream>
#include <string.h>
using namespace std;

const int num_chars = 26;
class Trie {
public:
       Trie();
       Trie(Trie& tr);
     virtual ~Trie();
     int trie_search(const char* word, char* entry ) const;
     int insert(const char* word, const char* entry);
// int remove(const char* word, char* entry);
protected:
     struct Trie_node
     {
         char* data;
           Trie_node* branch[num_chars];
           Trie_node();
     };
    
       Trie_node* root;
};
Trie::Trie_node::Trie_node()
{
      data = NULL;
    for (int i=0; i<num_chars; ++i)
          branch[i] = NULL;
}
Trie::Trie():root(NULL)
{
}
Trie::~Trie()
{
}
int Trie::trie_search(const char* word, char* entry ) const
{
    int position = 0;
    char char_code;
      Trie_node *location = root;
    while( location!=NULL && *word!=0 )
    {
        if (*word>='A' && *word<='Z')
              char_code = *word-'A';
        else if (*word>='a' && *word<='z')
              char_code = *word-'a';
        else return 0;
          location = location->branch[char_code];
          position++;
          word++;
    }
    if ( location != NULL && location->data != NULL )
    {
        strcpy(entry,location->data);
        return 1;
    }
    else return 0;
}
int Trie::insert(const char* word, const char* entry)
{
    int result = 1, position = 0;
    if ( root == NULL ) root = new Trie_node;
    char char_code;
      Trie_node *location = root;
    while( location!=NULL && *word!=0 )
    {
        if (*word>='A' && *word<='Z')
              char_code = *word-'A';
        else if (*word>='a' && *word<='z')
              char_code = *word-'a';
        else return 0;
        if( location->branch[char_code] == NULL )
              location->branch[char_code] = new Trie_node;
          location = location->branch[char_code];
          position++;
          word++;
    }
    if (location->data != NULL)
          result = 0;
    else {
          location->data = new char[strlen(entry)+1];
        strcpy(location->data, entry);
    }
    return result;
}
int main()
{
      Trie t;
char entry[100];
      t.insert("aa", "DET");
      t.insert("abacus","NOUN");
      t.insert("abalone","NOUN");
      t.insert("abandon","VERB");
      t.insert("abandoned","ADJ");
      t.insert("abashed","ADJ");
      t.insert("abate","VERB");
      t.insert("this", "PRON");
    if (t.trie_search("this", entry))
        cout<<"'this' was found. pos: "<<entry<<endl;
    if (t.trie_search("abate", entry))
        cout<<"'abate' is found. pos: "<<entry<<endl;
    if (t.trie_search("baby", entry))
        cout<<"'baby' is found. pos: "<<entry<<endl;
    else
        cout<<"'baby' does not exist at all!"<<endl;
   
    if (t.trie_search("aa", entry))
        cout<<"'aa was found. pos: "<<entry<<endl;

 system("pause");
return 0;
}