Autocomplete System with Trie in DSA Javascript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new Trie node with an empty children object.

DSA Javascript

class TrieNode {
  constructor() {
    this.children = [1];
    this.isEndOfWord = false;
  }
}

Drag options to blanks, or click blank then click option'

A{}

Bnull

C[]

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Using an array [] instead of an object for children.

Setting children to null or empty string.

The children of a Trie node should be an empty object to hold child nodes by character keys.

2fill in blank

medium

Complete the code to insert a character into the Trie children if it does not exist.

DSA Javascript

insert(word) {
  let node = this.root;
  for (let char of word) {
    if (!node.children.hasOwnProperty([1])) {
      node.children[char] = new TrieNode();
    }
    node = node.children[char];
  }
  node.isEndOfWord = true;
}

Drag options to blanks, or click blank then click option'

Achar

Bchildren

Cnode

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word' or 'node' instead of 'char' as the key.

Checking children without using hasOwnProperty.

We check if the current character 'char' exists as a key in the children object.

3fill in blank

hard

Fix the error in the search method to correctly check if a word exists in the Trie.

DSA Javascript

search(word) {
  let node = this.root;
  for (let char of word) {
    if (!node.children[[1]]) {
      return false;
    }
    node = node.children[char];
  }
  return node.isEndOfWord;
}

Drag options to blanks, or click blank then click option'

Anode

Bword

Cchar

Dchildren

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word' or 'node' instead of 'char' as the key.

Checking children without proper key.

We must check if the current character 'char' exists in the children object.

4fill in blank

hard

Fill both blanks to complete the DFS helper function that collects all words starting from a node.

DSA Javascript

dfs(node, prefix, results) {
  if (node.isEndOfWord) {
    results.push([1]);
  }
  for (let char in node.children) {
    this.dfs(node.children[char], prefix [2] char, results);
  }
}

Drag options to blanks, or click blank then click option'

Aprefix

Bprefix + char

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Pushing the wrong variable instead of prefix.

Using '-' instead of '+' for string concatenation.

Push the current prefix as a word when isEndOfWord is true, and concatenate prefix and char with '+' when recursing.

5fill in blank

hard

Fill the blanks to complete the autocomplete method that returns all words starting with a prefix.

DSA Javascript

autocomplete(prefix) {
  let node = this.root;
  for (let char of prefix) {
    if (!node.children[[1]]) {
      return [];
    }
    node = node.children[char];
  }
  let results = [];
  this.dfs(node, [2], results);
  return results;
}

Drag options to blanks, or click blank then click option'

Aprefix

Bchar

D''

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'prefix' instead of 'char' in the loop check.

Passing empty string instead of prefix to dfs.

Check if the current character 'char' exists in children, then call dfs with the full prefix string to collect words.