trie + 长度优先匹配，生成串

import com.google.common.collect.Maps;
import java.util.Map;
/**
 * tree  节点
 * Created by shuly on 16-7-18.
 */
public class Node {
    boolean isRoot;
    boolean isEnd;
    int cnt;

    Map<Character,Node> childrens;

    public Node(){
        if (childrens == null) childrens = Maps.newHashMap();
        this.cnt = 0;
    }
    public Node(boolean _isRoot,boolean _isEnd){
        if (childrens == null) childrens = Maps.newHashMap();
        setEnd(_isEnd);
        setRoot(_isRoot);
        this.cnt = 0;
    }
    public boolean isRoot() {
        return isRoot;
    }

    public void setRoot(boolean root) {
        isRoot = root;
    }

    public boolean isEnd() {
        return isEnd;
    }

    public void setEnd(boolean end) {
        isEnd = end;
    }

    public int getCnt() {
        return cnt;
    }

    public void setCnt(int cnt) {
        this.cnt = cnt;
    }

    public Map<Character, Node> getChildrens() {
        return childrens;
    }

    public void setChildrens(Map<Character, Node> childrens) {
        this.childrens = childrens;
    }
}

import com.google.common.collect.Lists;
import java.util.Stack;
import java.io.*;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

/**
 * 树的主类
 * Created by shuly on 16-7-18.
 */
public class PyTreeIT {
    Node ROOT;

    public PyTreeIT() {
        ROOT = new Node(true,false);
        numberLimit = new Integer(20);
        URL url = PyTreeIT.class.getClassLoader().getResource("pyDic");
        String dicFilePath = url.getPath();
        File dicFile = new File(dicFilePath);
        BufferedReader br = null ;
        try {
            String line;
            br = new BufferedReader(new InputStreamReader(new FileInputStream(dicFile), "UTF-8"));
            while((line = br.readLine()) != null)
            {
                String  word = line.trim();
                this.insert(word);
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        finally {
            if(br != null){
                try {
                    br.close();
                }
                catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
    public void insert(String word){
        Node root= ROOT;
        char [] words = word.toCharArray();
        for(int i = 0 ; i< words.length ; ++i){
            Character key = words[i];
            if(!root.getChildrens().containsKey(key)){
                root.getChildrens().put(key,new Node(false,false));
            }
            root = root.getChildrens().get(key);
            root.setCnt(root.getCnt()+1);
        }
        root.setEnd(true);
    }
    public int  had(String word){
        Node root = ROOT;
        char[] words = word.toCharArray();
        for(int i = 0 ; i< words.length ; ++i){
            Character key = words[i];
            if(root.getChildrens().containsKey(key)){
                root = root.getChildrens().get(key);
            }else
                return -1;
        }
        return root.isEnd()? root.getCnt(): 0;
    }
    static class InStack{
        public String key,left;
        public InStack(String _key,String _left){
            this.key = _key;
            this.left = _left;
        }
        @Override
        public String toString(){
            return key +"--" + left;
        }
    }
    protected Integer numberLimit;
    private List<List<String>> dfs(String word) {
        if(word != null && word.equals("")){
            return new ArrayList<List<String>>();
        }
        List<List<String>> ans = Lists.newArrayList();
        Stack<InStack> stack = new Stack<InStack>();
        int pos = 0;
        stack.clear();
        Node root = ROOT;
        while( pos < word.length() && root.getChildrens().containsKey(word.charAt(pos))) {
            root = root.getChildrens().get(word.charAt(pos));
            if (root.isEnd()) {
                stack.push(new InStack(word.substring(0, pos + 1), word.substring(pos + 1)));
            }
            if (root.getCnt() == 1) {
                break;
            }
            ++ pos ;
        }
        while(!stack.empty()){
            InStack now = stack.pop();
            //末尾
            if(now.left.equals("")){
                List<String> inList = Lists.newArrayList();
                inList.add(now.key);
                ans.add(inList);
                if(ans.size() == numberLimit){
                    return ans;
                }
                continue;
            }
            //非末尾
            List<List<String>> leftStringList = dfs(now.left);
            for(List<String> item : leftStringList){
                List<String> inList = Lists.newArrayList();
                inList.add(now.key);
                inList.addAll(item);
                ans.add(inList);
                if(ans.size() == numberLimit){
                    return ans;
                }
            }
        }
        return ans;
    }



    public List<List<String>> pySplit(String word,Integer number){
        numberLimit = number==null? 20:number;
        if(word.length() >= 60){
            return new ArrayList< List<String> >();
        }
        else
            return dfs(word);
    }
    public static void main(String[] args){
        String it = "xiangangtiananmen";
        PyTreeIT pyTree = new PyTreeIT();
        List<List<String>>ans = pyTree.pySplit(it,20);
        if(ans == null){
            System.out.println("TOT");
        }
        else {
            for (List<String> item : ans) {
                for (String key : item) {
                    System.out.print(key);
                    System.out.print(" ");
                }
                System.out.println("");
            }
        }
        System.out.println("over");
    }
}