一個Trie字典樹的簡單實現

// 字典樹.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
using namespace std;
const int Max=26;
typedef struct Node
{
	bool isStr;
	Node *next[Max];
}TrieNode;
class Trie
{

public: 
	//構造函數中初始化根節點
	Trie()
	{
		root=new TrieNode;
		for(int i=0;i<Max;i++)
			root->next[i]=NULL;
		root->isStr=false;
	}
	//利用遞歸的方法將整個字典樹刪除
	~Trie()
	{
		del(root);
		root=NULL;
	}
	//字典樹的插入操作
	void insert(const char *str)
	{
		if(str==NULL||*str=='\0')
			return;
		TrieNode *p=root;
		while(*str!='\0')
		{
			if(p->next[*str-'a']==NULL)
			{
				TrieNode *tmp=new TrieNode;
				for(int i=0;i<Max;i++)
					tmp->next[i]=NULL;
				tmp->isStr=false;
				p->next[*str-'a']=tmp;
				p=tmp;
			}
			else
			{
				p=p->next[*str-'a'];
			}
			str++;
		}
		p->isStr=true;
	}
	//查找某一個字符是否在字典樹中存在
	bool search(const char *str)
	{
		if(str==NULL||*str=='\0')
			return false;
		TrieNode *p=root;
		while(p!=NULL && *str!='\0')
		{
			p=p->next[*str-'a'];
			str++;
		}
		if(p!=NULL && p->isStr==true)
			return true;
		else
			return false;
	}
protected:
	void del(TrieNode *root)
	{
		for(int i=0;i<Max;i++)
		{
			if(root->next[i]!=NULL)
			{
				del(root->next[i]);
			}
		}
		delete root;
	}
private:
	TrieNode *root;
};
int _tmain(int argc, _TCHAR* argv[])
{
	Trie trie;
	trie.insert("happy");
	trie.insert("girl");
	trie.insert("lady");
	if(trie.search("happy"))
		cout<<"Yes"<<endl;
	else
		cout<<"No"<<endl;
	
	if(trie.search("boy"))
		cout<<"Yes"<<endl;
	else
		cout<<"No"<<endl;
	
	if(trie.search("lady"))
		cout<<"Yes"<<endl;
	else
		cout<<"No"<<endl;
	
	if(trie.search("girl"))
		cout<<"Yes"<<endl;
	else
		cout<<"No"<<endl;
	system("pause");
	return 0;
}