Adjacency List Representation in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to initialize an empty adjacency list for a graph.

DSA Typescript

const adjacencyList: Record<number, number[]> = [1];

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

A[]

Bnew Map()

Cnull

D{}

Attempts:

3 left

💡 Hint

Common Mistakes

Using an empty array instead of an object.

Using null which is not a valid adjacency list.

Using Map without proper initialization.

We use an empty object {} to represent the adjacency list as a map from node to its neighbors.

2fill in blank

medium

Complete the code to add an edge from node 1 to node 2 in the adjacency list.

DSA Typescript

if (!adjacencyList[1]) adjacencyList[1] = [];
adjacencyList[1].[1](2);

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Apush

Bpop

Cshift

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop which removes the last element.

Using shift which removes the first element.

Using unshift which adds at the start, not end.

We use push to add node 2 to the neighbors of node 1.

3fill in blank

hard

Fix the error in the code to correctly add an undirected edge between nodes 3 and 4.

DSA Typescript

if (!adjacencyList[3]) adjacencyList[3] = [];
adjacencyList[3].push(4);
if (!adjacencyList[4]) adjacencyList[4] = [];
adjacencyList[4].[1](3);

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

Apush

Bpop

Cshift

Dunshift

Attempts:

3 left

💡 Hint

Common Mistakes

Using pop which removes elements instead of adding.

Using shift or unshift which are not appropriate here.

To add the edge back from node 4 to node 3, we use push to add 3 to adjacencyList[4].

4fill in blank

hard

Fill both blanks to create an adjacency list for nodes 1 to 3 with edges 1->2 and 2->3.

DSA Typescript

const adjacencyList = {
  1: [[1]],
  2: [[2]],
  3: []
};

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A2

B3

C1

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up which node connects to which.

Adding extra nodes or edges not specified.

Node 1 connects to 2, and node 2 connects to 3, so adjacencyList[1] = [2] and adjacencyList[2] = [3].

5fill in blank

hard

Fill all three blanks to add edges 5->6, 6->7, and 7->5 in the adjacency list.

DSA Typescript

const adjacencyList = {};

if (!adjacencyList[5]) adjacencyList[5] = [];
adjacencyList[5].push([1]);

if (!adjacencyList[6]) adjacencyList[6] = [];
adjacencyList[6].push([2]);

if (!adjacencyList[7]) adjacencyList[7] = [];
adjacencyList[7].push([3]);

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

A6

B7

C5

D8

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong neighbor numbers.

Forgetting to initialize adjacencyList entries.

Edges are 5->6, 6->7, and 7->5, so we push 6 to adjacencyList[5], 7 to adjacencyList[6], and 5 to adjacencyList[7].