Trie vs Hash Map for Prefix Matching in DSA Typescript - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to insert a word into the Trie.

DSA Typescript

insert(word: string): void {
  let node = this.root;
  for (const char of word) {
    if (!node.children.has(char)) {
      node.children.set(char, new TrieNode());
    }
    node = node.children.[1](char);
  }
  node.isEndOfWord = true;
}

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

Adelete

Bset

Chas

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'set' instead of 'get' to access a child node.

Using 'has' which returns a boolean, not the node.

We use 'get' to move to the child node corresponding to the current character.

2fill in blank

medium

Complete the code to check if a prefix exists in the Trie.

DSA Typescript

startsWith(prefix: string): boolean {
  let node = this.root;
  for (const char of prefix) {
    if (!node.children.[1](char)) {
      return false;
    }
    node = node.children.get(char)!;
  }
  return true;
}

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

Aget

Bset

Chas

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' which returns undefined if key not found, but here we want a boolean check.

Using 'set' which adds or updates a key.

'has' checks if the Map contains the given character key.

3fill in blank

hard

Fix the error in the Hash Map prefix search function to correctly check prefixes.

DSA Typescript

function hasPrefix(map: Map<string, boolean>, prefix: string): boolean {
  for (let i = 1; i <= prefix.length; i++) {
    const sub = prefix.slice(0, i);
    if (!map.[1](sub)) {
      return false;
    }
  }
  return true;
}

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

Ahas

Bget

Cset

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' which returns undefined if key not found, but here a boolean check is needed.

Using 'set' which modifies the Map.

We use 'has' to check if the map contains the prefix substring as a key.

4fill in blank

hard

Fill both blanks to create a Trie search method that returns true if a word exists.

DSA Typescript

search(word: string): boolean {
  let node = this.root;
  for (const char of word) {
    if (!node.children.[1](char)) {
      return false;
    }
    node = node.children.[2](char)!;
  }
  return node.isEndOfWord;
}

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

Ahas

Bget

Cset

Ddelete

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' before checking existence causes errors if key missing.

Using 'set' or 'delete' which modify the Map.

First check if the child exists with 'has', then get the child node with 'get'.

5fill in blank

hard

Fill all three blanks to build a Hash Map prefix insertion that stores all prefixes of a word.

DSA Typescript

function insertPrefixes(map: Map<string, boolean>, word: string): void {
  for (let i = 1; i <= word.length; i++) {
    const prefix = word.[1](0, i);
    map.[2](prefix, true);
  }
  map.[3](word, true);
}

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

Aslice

Bset

Chas

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'get' or 'has' instead of 'set' to add keys.

Using wrong string method like 'substr' or 'substring' inconsistently.

Use 'slice' to get prefixes, 'set' to add them to the map. The last line also uses 'set' to mark the full word.