字典树java版本

package trietree;

/*

* 字典树的基本数据结构

* 字典树的性质：

* 1：根节点无数据

* 2：除了根节点，每个节点都只有一个元素

* 3：从根节点到叶节点是一个完成的单词，每一个节点的子节点没有重复的

* */

public class TrieNode {

private int num;//当前节点出现的次数

private TrieNode[] son;

private boolean ieEnd;

private boolean visited;

private char val;

public TrieNode(char element){

this.num=1;

this.son=new TrieNode[26];

this.ieEnd=false;

this.visited=false;

this.val=element;

}

public TrieNode(){

this.num=1;

this.son=new TrieNode[26];

this.ieEnd=false;

this.visited=false;

}

public TrieNode(int num, TrieNode[] son, boolean ieEnd, boolean visited,

char val) {

super();

this.num = num;

this.son = son;

this.ieEnd = ieEnd;

this.visited = visited;

this.val = val;

}

public int getNum() {

return num;

}

public void setNum(int num) {

this.num = num;

}

public TrieNode[] getSon() {

return son;

}

public void setSon(TrieNode[] son) {

this.son = son;

}

public boolean isIeEnd() {

return ieEnd;

}

public void setIeEnd(boolean ieEnd) {

this.ieEnd = ieEnd;

}

public boolean isVisited() {

return visited;

}

public void setVisited(boolean visited) {

this.visited = visited;

}

public char getVal() {

return val;

}

public void setVal(char val) {

this.val = val;

}

@Override

public int hashCode() {

final int prime = 31;

int result = 1;

result = prime * result + val;

return result;

}

@Override

public boolean equals(Object obj) {

if (this == obj)

return true;

if (obj == null)

return false;

if (getClass() != obj.getClass())

return false;

TrieNode other = (TrieNode) obj;

if (val != other.val)

return false;

return true;

}

}

package trietree;

import java.util.LinkedList;

/*

* yy

* 1：字典树的插入

* 2：查找

* 3：统计前缀

* 4：遍历字典树

* */

public class TrieTree {

private TrieNode root;

public TrieNode getRoot() {

return root;

}

public void setRoot(TrieNode root) {

this.root = root;

}

public TrieTree(TrieNode root) {

super();

this.root = root;

}

public TrieTree() {

this.root=new TrieNode();

}

//向字典树插入一个字符串

public void insert(String str){

if(str==null||str.equalsIgnoreCase(""))return ;

TrieNode node=this.root;

char[] letters=str.toCharArray();

int len=str.length();

for(int i=0;i<len;i++){

int pos=letters[i]-'a';

if(node.getSon()[pos]==null){

node.getSon()[pos]=new TrieNode(letters[i]);

}else{

node.getSon()[pos].setNum(node.getSon()[pos].getNum()+1);

}

node=node.getSon()[pos];

}

node.setIeEnd(true);

}

//计算给定当前前缀有多少字符串

public int countPrefix(String prefix){

if(prefix==null || "".equalsIgnoreCase(prefix))return -1;

TrieNode node=this.root;

char[] letters=prefix.toCharArray();

int len=prefix.length();

for(int i=0;i<len;i++){

int pos=letters[i]-'a';

if(node.getSon()[pos]==null){

return 0;

}else{

node=node.getSon()[pos];

}

}

return node.getNum();

}

//查看当前的字典树是否包含某个单词

public boolean has(String str){

if(str==null||"".equalsIgnoreCase(str))return false;

TrieNode node=this.root;

char[] letters=str.toCharArray();

int len=str.length();

for(int i=0;i<len;i++){

int pos=letters[i]-'a';

if(node.getSon()[pos]==null){

return false;

}else{

node=node.getSon()[pos];

}

}

return node.isIeEnd();

}

//遍历当前的字典树

public void printALlWords(){

TrieNode rootnode=this.root;

if(rootnode==null)return ;

LinkedList<TrieNode> list=new LinkedList<TrieNode>();

for(int i=0;i<26;i++){

TrieNode node=rootnode.getSon()[i];

if(node!=null){

list.addLast(node);

while(!list.isEmpty()){

TrieNode current=list.getLast();

TrieNode firstChild=firstOfChild(current);

while(firstChild!=null){

list.addLast(firstChild);

firstChild=firstOfChild(firstChild);

}

TrieNode last=list.getLast();

if(last.isIeEnd()==true){

this.printList(list);

}

list.removeLast();

}

}

list.clear();

}

}

//返回当前节点的第一个孩子

private TrieNode firstOfChild(TrieNode current) {

if(current==null)return null;

for(int i=0;i<26;i++){

if(current.getSon()[i]!=null&¤t.getSon()[i].isVisited()==false){

current.getSon()[i].setVisited(true);

return current.getSon()[i];

}

}

return null;

}

private void printList(List<TrieNode> list){

if(list==null||list.size()==0)return ;

for(TrieNode node:list){

System.out.print(node.getVal());

}

System.out.println();

}

public static void main(String[] args) {

TrieTree tree=new TrieTree();

String[] strs={"bee","banana", "band","absolute", "acm"}; //

String[] prefix={

"ba",

"b",

"band",

"abc"

};

for(String s:strs){

tree.insert(s);

}

for(String pre:prefix){

System.out.println(pre+":"+tree.countPrefix(pre));

}

System.out.println(tree.has("banana"));

System.out.println(tree.has("ba"));

tree.printALlWords();

}

}