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package DataStructures.Trees;

/**

* 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);

}

}

}

}