PrefixString.java

package com.company;
import java.util.*;

public class Trie {
    public static void main(String[] args) {
//        String s = "tttt";
        Trie t = new Trie();
//        t.insert(s);
//        t.insert("ttt");
//        System.out.println(t.startsWith("tt"));
        String [] a = {"one", "two", "three"};
        List<String> list = Arrays.asList(a);
        String [] b = {"onetwo", "two"};
        for(String s: a){
            t.insert(s);
        }
        for(String s: b){
            HashMap<String, Integer> map = new HashMap<>();
            // return false if
            for(String word: a){
                int index = s.indexOf((word));
                if(index > -1){
                    map.put(word, index);
                }
            }
            Set<String> keys = map.keySet(); //


        }

    }

    class Node {
        Node[] children = new Node[26];
        boolean isCompleted;
    }

    private Node root;

    public Trie() {
        root = new Node();
    }

    public void insert(String s) {
        Node node = root;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (node.children[c - 'a'] == null) {
                node.children[c - 'a'] = new Node();
            }
            node = node.children[c - 'a']; // moves pointer down.
        }
        node.isCompleted = true;
    }

    public boolean search(String word) {
        Node node = searchNode(word);
        if (node == null) {
            return false;
        }
        return node.isCompleted;
    }

    public boolean startsWith(String prefix) {
        Node node = searchNode(prefix);
        if (node == null) {
            return false;
        }
        return true;
    }

    public Node searchNode(String s) {
        Node node = root;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (node.children[c - 'a'] == null) {
                return null;
            } else {
                node = node.children[c - 'a'];
            }
        }
        return node;
    }

}