Tree vs Array vs Linked List When Hierarchy Matters in DSA Typescript - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a simple tree node with a value.

DSA Typescript

class TreeNode {
  value: number;
  children: TreeNode[];
  constructor(value: number) {
    this.value = value;
    this.children = [1];
  }
}

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

Anull

B{}

C[]

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using {} instead of [] for children.

Setting children to null or 0.

The children property should be an empty array to hold child nodes.

2fill in blank

medium

Complete the code to add a child node to a tree node.

DSA Typescript

function addChild(parent: TreeNode, child: TreeNode): void {
  parent.children.[1](child);
}

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

Apush

Bshift

Cpop

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop which removes the last element.

Using shift or unshift which affect the start of the array.

push adds the child node to the end of the children array.

3fill in blank

hard

Fix the error in the linked list node definition to correctly link nodes.

DSA Typescript

class ListNode {
  value: number;
  next: [1] | null;
  constructor(value: number) {
    this.value = value;
    this.next = null;
  }
}

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

Aboolean

Bnumber

Cstring

DListNode

Attempts:

3 left

💡 Hint

Common Mistakes

Using primitive types like number or string for next.

Forgetting to allow null for the last node.

The next property should be of type ListNode to link to the next node.

4fill in blank

hard

Fill both blanks to create a function that converts an array to a linked list.

DSA Typescript

function arrayToLinkedList(arr: number[]): ListNode | null {
  if (arr.length === 0) return null;
  const head = new ListNode(arr[0]);
  let current = head;
  for (let i = 1; i [1] arr.length; i++) {
    current.next = new ListNode(arr[[2]]);
    current = current.next;
  }
  return head;
}

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

A<

Bi

C<=

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using <= causes out-of-bounds error.

Using 0 instead of i for array index.

The loop runs while i < arr.length and uses arr[i] to create new nodes.

5fill in blank

hard

Fill both blanks to create a function that prints tree values in preorder.

DSA Typescript

function preorder(node: TreeNode | null): void {
  if (node === null) return;
  console.log(node.[1]);
  for (const child of node.[2]) {
    preorder(child);
  }
}

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

Avalue

Bchildren

C)

D(

Attempts:

3 left

💡 Hint

Common Mistakes

Missing parentheses in recursive call.

Using wrong property names.

Print node.value, loop over node.children, and call preorder(child) with parentheses.