Trie Tree的c++实现

时间：2014-05-01 17:33:50 收藏：0 阅读：362

问题描述：

1.Tire tree 是一种用来存储字符串的高效的数据结构。它的插入和查询的时间复杂度为O(string length)。用self balance tree 存储字符串的时间复杂度为O(length(string)*lgN)，N是树的节点树。Trie tree的查询和存储优势是很显然的；

2.它的缺点是树的存储空间变大，需要更多的内存；

3.它的每个节点会有多个孩子节点，同一节点下的孩子共享相同的前缀串（从根节点到父节点的字符串）；

4.详细可见下图：

mamicode.com,码迷

程序代码：

#ifndef _TRIE_TREE_H_
#define _TRIE_TREE_H_

#include <stdlib.h>
#include <assert.h>
#include <string>
#include <iostream>

/*
*
*
*/
class TrieTree
{
public:
	static const int MAX_BRANCH_SIZE = 26;

	// tree node
	typedef struct tagTireNode
	{
		tagTireNode* child[MAX_BRANCH_SIZE];
		int          leafFlag;

		tagTireNode():leafFlag(-1)
		{
			memset( child, 0x00, sizeof(child) );
		}

	}TrieNode, *pTireNode;


	TrieTree():m_root(new TrieNode), m_count(0)
	{

	}

	~TrieTree()
	{
		Clear();
	}

	/*
	* Clear all node
	*
	*/
	void Clear()
	{
		Clear( m_root );
	}

	/*
	* search string 
	*
	*/
	bool Search( const char* word )
	{
		pTireNode cur = m_root;
		size_t depth = strlen( word );

		for( size_t i = 0; i < depth; i++ )
		{
			int idx = CharToIndex( word[i] );
			if( !cur->child[idx] )
			{
				return false;
			}

			cur = cur->child[idx];
		}

		return cur;
	}

	/*
	* Insert string to tree
	*
	*/
	void Insert( const char* word )
	{
		pTireNode cur = m_root;
		size_t depth = strlen( word );
		for( size_t i = 0; i < depth; i++ )
		{
			int idx = CharToIndex( word[i] );
			if( !cur->child[idx] )
			{
				if( 0 == i )
					m_count++;

				cur->child[idx] = new TrieNode;
			}

			cur = cur->child[idx];
		}

		cur->leafFlag = 0;
	}

	/*
	* Compress output tree
	*
	*/
	void OuputCompressTree( std::string& output )
	{
		OuputCompressTree( output, m_root );
	}


private:

	void OuputCompressTree( std::string& output, pTireNode root )
	{	
		for( size_t i = 0; i < MAX_BRANCH_SIZE; i++ )
		{
			if( root->child[i] )
			{
				char c = IndexToChar( i );
				output += c;

				if( 0 == root->leafFlag )
				{
					return;
				}
				else
				{
					OuputCompressTree( output, root->child[i] );
				}

			}
		}

	}

	/*
	*
	*
	*/
	void Clear( pTireNode& node )
	{
		if( 0 == node )
			return;

		for( size_t i = 0; i < MAX_BRANCH_SIZE; i++ )
		{
			Clear( node->child[i] );
		}

		delete node;
		node = 0;
	}

	/*
	*
	*
	*/
	int CharToIndex( char input )
	{
		return (int)(input - ‘a‘);
	}

	/*
	*
	*
	*/
	char IndexToChar( int idx )
	{
		return (char)( idx + ‘a‘);
	}

private:

	pTireNode  m_root;
	size_t     m_count;


};

/*
* Test interface
*
*/
void TestTrieTree()
{
	char* words[] = {"the", "a", "there", "answer", "any", "by", "bye", "their", "ant", "these", "heap",
	                  "dynamic", "day", "micro", "meter", "mimic", "soul","such", "many", "metal" };
	size_t size = sizeof(words)/sizeof(words[0]);

	TrieTree tree;
	for( int i = 0; i < size; i++ )
	{
		tree.Insert( words[i] );
	}

	for( int i = 0; i < size; i++ )
	{
		assert( tree.Search( words[i] ) );
	}

	assert( tree.Search("man") );
	assert( tree.Search("met") );
	assert( tree.Search("so" ) );
	assert( !tree.Search("bee"));
	assert( !tree.Search("at") );

	std::string outputBuf;
	tree.OuputCompressTree( outputBuf );
	std::cout << outputBuf.c_str() << std::endl;


}


#endif

compile and run in visual studio 2005

Trie Tree的c++实现,码迷,mamicode.com