字典树

代码实现

Java

packagecom.suning.search.test.tree.trie;

public class Trie{
private int SIZE=26;
private TrieNode root;//字典树的根

Trie(){//初始化字典树
root=new TrieNode();
}

private class TrieNode{//字典树节点
private int num;//有多少单词通过这个节点,即节点字符出现的次数
private TrieNode[]  son;//所有的儿子节点
private boolean isEnd;//是不是最后一个节点
private char val;//节点的值

TrieNode(){
num=1;
son=new TrieNode[SIZE];
isEnd=false;
}
}

//建立字典树
public void insert(String str){//在字典树中插入一个单词
if(str==null||str.length()==0){
return;
}
TrieNode node=root;
char[]letters=str.toCharArray();
for(inti=0,len=str.length();i<len;i++){
int pos=letters[i]-'a';
if(node.son[pos]==null){
node.son[pos]=newTrieNode();
node.son[pos].val=letters[i];
}else{
node.son[pos].num++;
}
node=node.son[pos];
}
node.isEnd=true;
}

//计算单词前缀的数量
public int countPrefix(Stringprefix){
if(prefix==null||prefix.length()==0){
return-1;
}
TrieNode node=root;
char[]letters=prefix.toCharArray();
for(inti=0,len=prefix.length();i<len;i++){
int pos=letters[i]-'a';
if(node.son[pos]==null){
return 0;
}
else{
node=node.son[pos];
}
}
return node.num;
}
//打印指定前缀的单词
public String hasPrefix(String prefix) {
if (prefix == null || prefix.length() == 0) {
return null;
}
TrieNode node = root;
char[] letters = prefix.toCharArray();
for (int i = 0, len = prefix.length(); i < len; i++) {
int pos = letters[i] - 'a';
if (node.son[pos] == null) {
return null;
} else {
node = node.son[pos];
}
}
preTraverse(node, prefix);
return null;
}
// 遍历经过此节点的单词.
public void preTraverse(TrieNode node, String prefix) {
if (!node.isEnd){
for (TrieNode child : node.son) {
if (child!=null){
preTraverse(child, prefix+child.val);
}
}
return;
}
System.out.println(prefix);
}

//在字典树中查找一个完全匹配的单词.
public boolean has(Stringstr){
if(str==null||str.length()==0){
return false;
}
TrieNode node=root;
char[]letters=str.toCharArray();
for(inti=0,len=str.length();i<len;i++){
intpos=letters[i]-'a';
if(node.son[pos]!=null){
node=node.son[pos];
}else{
return false;
}
}
return node.isEnd;
}

//前序遍历字典树.
public void preTraverse(TrieNodenode){
if(node!=null){
System.out.print(node.val+"-");
for(TrieNodechild:node.son){
preTraverse(child);
}
}
}

public TrieNode getRoot(){
return this.root;
}

public static void main(String[]args){
Trietree=newTrie();
String[]strs={"banana","band","bee","absolute","acm",};
String[]prefix={"ba","b","band","abc",};
for(Stringstr:strs){
tree.insert(str);
}
System.out.println(tree.has("abc"));
tree.preTraverse(tree.getRoot());
System.out.println();
//tree.printAllWords();
for(Stringpre:prefix){
int num=tree.countPrefix(pre);
System.out.println(pre+""+num);
}
}
}

C语言

#define MAX 26//字符集大小
typedef struct TrieNode
{
int nCount;//记录该字符出现次数
struct TrieNode* next[MAX];
}TrieNode;

TrieNode Memory[1000000];
int allocp=0;

/*初始化*/
void InitTrieRoot(TrieNode* *pRoot)
{
*pRoot=NULL;
}

/*创建新结点*/
TrieNode* CreateTrieNode()
{
int i;
TrieNode *p;
p=&Memory[allocp++];
p->nCount=1;
for(i=0;i<MAX;i++)
{
p->next[i]=NULL;
}
return p;
}

/*插入*/
void InsertTrie(TrieNode* *pRoot,char *s)
{
inti,k;
TrieNode*p;
if(!(p=*pRoot))
{
p=*pRoot=CreateTrieNode();
}
i=0;
while(s[i])
{
k=s[i++]-'a';//确定branch
if(!p->next[k])
p->next[k]=CreateTrieNode();
p->next[k]->nCount++;
p=p->next[k];
}
}

//查找
int SearchTrie(TrieNode* *pRoot,char *s)
{
TrieNode *p;
int i,k;
if(!(p=*pRoot))
{
return0;
}
i=0;
while(s[i])
{
k=s[i++]-'a';
if(p->next[k]==NULL) return 0;
p=p->next[k];
}
return p->nCount;
}

C++

#include<cstring>
#include<iostream>
#include<conio.h>
usingnamespacestd;
namespacetrie
{
template<classT,size_tCHILD_MAX>
/*
ParameterT:Typeofreserveddata.
ParameterCHILD_MAX:Sizeofarryofpointerstochildnode.
*/
structnod
{
Treserved;
nod<T,CHILD_MAX>*child[CHILD_MAX];
nod()
{
memset(this,0,sizeof*this);
}
~nod()
{
for(unsignedi=0;i<CHILD_MAX;i++)
deletechild[i];
}
voidTraversal(char*str,unsignedindex)
{
unsignedi;
for(i=0;i<index;i++)
cout<<str[i];
cout<<'\t'<<reserved<<endl;
for(i=0;i<CHILD_MAX;i++)
{
if(child[i])
{
str[index]=i;
child[i]->Traversal(str,index+1);
}
}
return;
}
};

template<classT,size_tCHILD_MAX=127>
/*
ParameterT:Typeofreserveddata.
ParameterCHILD_MAX:Sizeofarryofpointerstochildnode.
*/
classtrie
{
private:
nod<T,CHILD_MAX>root;
public:
nod<T,CHILD_MAX>*AddStr(char*str);
nod<T,CHILD_MAX>*FindStr(char*str);
boolDeleteStr(char*str);
voidTraversal()
{
charstr[100];
root.Traversal(str,0);
}
};

template<classT,size_tCHILD_MAX>
nod<T,CHILD_MAX>*trie<T,CHILD_MAX>::AddStr(char*str)
{
nod<T,CHILD_MAX>*now=&root;
do
{
if(now->child[*str]==NULL)
now->child[*str]=newnod<T,CHILD_MAX>;
now=now->child[*str];
}while(*(++str)!='\0');
returnnow;
}

template<classT,size_tCHILD_MAX>
nod<T,CHILD_MAX>*trie<T,CHILD_MAX>::FindStr(char*str)
{
nod<T,CHILD_MAX>*now=&root;
do
{
if(now->child[*str]==NULL)
returnNULL;
now=now->child[*str];
}while(*(++str)!='\0');
returnnow;
}

template<classT,size_tCHILD_MAX>
booltrie<T,CHILD_MAX>::DeleteStr(char*str)
{
nod<T,CHILD_MAX>**nods=newnod<T,CHILD_MAX>*[strlen(str)];
intsnods=1;
nod<T,CHILD_MAX>*now=&root;
nods[0]=&root;
do
{
if(now->child[*str]==NULL)
returnfalse;
nods[snods++]=now=now->child[*str];
}while(*(++str)!='\0');
snods--;
while(snods>0)
{
for(unsignedi=0;i<CHILD_MAX;i++)
if(nods[snods]->child[i]!=NULL)
returntrue;
deletenods[snods];
nods[--snods]->child[*(--str)]=NULL;
}
returntrue;
}
}
intmain()
{
//TestProgram
trie::trie<int>tree;
while(1)
{
cout<<"1foraddastring"<<endl;
cout<<"2forfindastring"<<endl;
cout<<"3fordeleteastring"<<endl;
cout<<"4fortraversal"<<endl;
cout<<"5forexit"<<endl;
charstr[100];
switch(getch())
{
case'1':
cin.getline(str,100);
cout<<"Thisstinghasexistedfor"<<tree.AddStr(str)->reserved++<<"times."<<endl;
break;
case'2':
cin.getline(str,100);
trie::nod<int,127>*find;
find=tree.FindStr(str);
if(!find)
cout<<"Nofound."<<endl;
else
cout<<"Thisstinghasexistedfor"<<find->reserved<<"times."<<endl;
break;
case'3':
cin.getline(str,100);
cout<<"Theactionis"<<(tree.DeleteStr(str)?"Successful.":"Unsuccessful.")<<endl;
break;
case'4':
tree.Traversal();
break;
case'5':
return0;
}
}
return0;
}