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TrieImp.java

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//Trie Data structure implementation without any libraries */

/**

*

* @author Dheeraj Kumar Barnwal (https://github.com/dheeraj92)

*

*/

import java.util.Scanner;

public class TrieImp {

public class TrieNode {

TrieNode[] child;

boolean end;

public TrieNode(){

child = new TrieNode[26];

end = false;

}

}

private final TrieNode root;

public TrieImp(){

root = new TrieNode();

}

public void insert(String word){

TrieNode currentNode = root;

for(int i=0; i < word.length();i++){

TrieNode node = currentNode.child[word.charAt(i)-'a'];

if(node == null){

node = new TrieNode();

currentNode.child[word.charAt(i)-'a']=node;

}

currentNode = node;

}

currentNode.end = true;

}

public boolean search(String word){

TrieNode currentNode = root;

for(int i=0;i<word.length();i++){

char ch = word.charAt(i);

TrieNode node = currentNode.child[ch-'a'];

if(node == null){

return false;

}

currentNode = node;

}

return currentNode.end;

}

public boolean delete(String word){

TrieNode currentNode = root;

for(int i=0;i<word.length();i++){

char ch = word.charAt(i);

TrieNode node = currentNode.child[ch-'a'];

if(node == null){

return false;

}

currentNode = node;

}

if(currentNode.end == true){

currentNode.end = false;

return true;

}

return false;

}

public static void sop(String print){

System.out.println(print);

}

//Regex to check if word contains only a-z character

public static boolean isValid(String word){

return word.matches("^[a-z]+$");

}

public static void main(String[] args) {

TrieImp obj = new TrieImp();

String word;

@SuppressWarnings("resource")

Scanner scan = new Scanner(System.in);

sop("string should contain only a-z character for all operation");

while(true){

sop("1. Insert\n2. Search\n3. Delete\n4. Quit");

try{

int t = scan.nextInt();

switch (t) {

case 1:

word = scan.next();

if(isValid(word))

obj.insert(word);

else

sop("Invalid string: allowed only a-z");

break;

case 2:

word = scan.next();

boolean resS=false;

if(isValid(word))

resS = obj.search(word);

else

sop("Invalid string: allowed only a-z");

if(resS)

sop("word found");

else

sop("word not found");

break;

case 3:

word = scan.next();

boolean resD=false;

if(isValid(word))

resD = obj.delete(word);

else

sop("Invalid string: allowed only a-z");

if(resD){

sop("word got deleted successfully");

}else{

sop("word not found");

}

break;

case 4:

sop("Quit successfully");

System.exit(1);

break;

default:

sop("Input int from 1-4");

break;

}

}catch(Exception e){

String badInput = scan.next();

sop("This is bad input: " + badInput);

}

}

}

}