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:
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
时间: 2024-10-29 19:05:29