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Improve TrieImp.java comments & enhance readability (#5526)

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This commit is contained in:
Hardik Pawar
2024-10-05 15:17:52 +05:30
committed by GitHub
parent 87871efcdb
commit ce34595628
3 changed files with 156 additions and 77 deletions
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130
src/main/java/com/thealgorithms/datastructures/trees/TrieImp.java
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@ -1,19 +1,35 @@
package com.thealgorithms.datastructures.trees;
import java.util.Scanner;
/**
* Trie Data structure implementation without any libraries
* Trie Data structure implementation without any libraries.
* <p>
* The Trie (also known as a prefix tree) is a special tree-like data structure
* that is used to store a dynamic set or associative array where the keys are
* usually strings. It is highly efficient for prefix-based searches.
* <p>
* This implementation supports basic Trie operations like insertion, search,
* and deletion.
* <p>
* Each node of the Trie represents a character and has child nodes for each
* possible character.
*
* @author <a href="https://github.com/dheeraj92">Dheeraj Kumar Barnwal</a>
*/
public class TrieImp {
/**
* Represents a Trie Node that stores a character and pointers to its children.
* Each node has an array of 26 children (one for each letter from 'a' to 'z').
*/
public class TrieNode {
TrieNode[] child;
boolean end;
/**
* Constructor to initialize a TrieNode with an empty child array
* and set end to false.
*/
public TrieNode() {
child = new TrieNode[26];
end = false;
@ -22,10 +38,22 @@ public class TrieImp {
private final TrieNode root;
/**
* Constructor to initialize the Trie.
* The root node is created but doesn't represent any character.
*/
public TrieImp() {
root = new TrieNode();
}
/**
* Inserts a word into the Trie.
* <p>
* The method traverses the Trie from the root, character by character, and adds
* nodes if necessary. It marks the last node of the word as an end node.
*
* @param word The word to be inserted into the Trie.
*/
public void insert(String word) {
TrieNode currentNode = root;
for (int i = 0; i < word.length(); i++) {
@ -39,6 +67,16 @@ public class TrieImp {
currentNode.end = true;
}
/**
* Searches for a word in the Trie.
* <p>
* This method traverses the Trie based on the input word and checks whether
* the word exists. It returns true if the word is found and its end flag is
* true.
*
* @param word The word to search in the Trie.
* @return true if the word exists in the Trie, false otherwise.
*/
public boolean search(String word) {
TrieNode currentNode = root;
for (int i = 0; i < word.length(); i++) {
@ -52,6 +90,17 @@ public class TrieImp {
return currentNode.end;
}
/**
* Deletes a word from the Trie.
* <p>
* The method traverses the Trie to find the word and marks its end flag as
* false.
* It returns true if the word was successfully deleted, false if the word
* wasn't found.
*
* @param word The word to be deleted from the Trie.
* @return true if the word was found and deleted, false if it was not found.
*/
public boolean delete(String word) {
TrieNode currentNode = root;
for (int i = 0; i < word.length(); i++) {
@ -69,75 +118,26 @@ public class TrieImp {
return false;
}
/**
* Helper method to print a string to the console.
*
* @param print The string to be printed.
*/
public static void sop(String print) {
System.out.println(print);
}
/**
* Regex to check if word contains only a-z character
* Validates if a given word contains only lowercase alphabetic characters
* (a-z).
* <p>
* The method uses a regular expression to check if the word matches the pattern
* of only lowercase letters.
*
* @param word The word to be validated.
* @return true if the word is valid (only a-z), false otherwise.
*/
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);
}
}
}
}

76
src/test/java/com/thealgorithms/datastructures/trees/TrieImpTest.java Normal file
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@ -0,0 +1,76 @@
package com.thealgorithms.datastructures.trees;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
public class TrieImpTest {
private TrieImp trie;
@BeforeEach
public void setUp() {
trie = new TrieImp();
}
@Test
public void testInsertAndSearchBasic() {
String word = "hello";
trie.insert(word);
assertTrue(trie.search(word), "Search should return true for an inserted word.");
}
@Test
public void testSearchNonExistentWord() {
String word = "world";
assertFalse(trie.search(word), "Search should return false for a non-existent word.");
}
@Test
public void testInsertAndSearchMultipleWords() {
String word1 = "cat";
String word2 = "car";
trie.insert(word1);
trie.insert(word2);
assertTrue(trie.search(word1), "Search should return true for an inserted word.");
assertTrue(trie.search(word2), "Search should return true for another inserted word.");
assertFalse(trie.search("dog"), "Search should return false for a word not in the Trie.");
}
@Test
public void testDeleteExistingWord() {
String word = "remove";
trie.insert(word);
assertTrue(trie.delete(word), "Delete should return true for an existing word.");
assertFalse(trie.search(word), "Search should return false after deletion.");
}
@Test
public void testDeleteNonExistentWord() {
String word = "nonexistent";
assertFalse(trie.delete(word), "Delete should return false for a non-existent word.");
}
@Test
public void testInsertAndSearchPrefix() {
String prefix = "pre";
String word = "prefix";
trie.insert(prefix);
trie.insert(word);
assertTrue(trie.search(prefix), "Search should return true for an inserted prefix.");
assertTrue(trie.search(word), "Search should return true for a word with the prefix.");
assertFalse(trie.search("pref"), "Search should return false for a prefix that is not a full word.");
}
@Test
public void testIsValidWord() {
assertTrue(TrieImp.isValid("validword"), "Word should be valid (only lowercase letters).");
assertFalse(TrieImp.isValid("InvalidWord"), "Word should be invalid (contains uppercase letters).");
assertFalse(TrieImp.isValid("123abc"), "Word should be invalid (contains numbers).");
assertFalse(TrieImp.isValid("hello!"), "Word should be invalid (contains special characters).");
assertFalse(TrieImp.isValid(""), "Empty string should be invalid.");
}
}