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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);
}
}
}
}