Graph representations (adjacency matrix vs list) in Data Structures Theory - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an adjacency matrix for a graph with 3 nodes.

Data Structures Theory

adj_matrix = [[0 for _ in range(3)] for _ in range([1])]

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

A3

B2

C4

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong size for the matrix, like 2 or 4 instead of 3.

The adjacency matrix for a graph with 3 nodes must be a 3x3 matrix, so the range should be 3.

2fill in blank

medium

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

Data Structures Theory

adj_list = {0: [], 1: [], 2: []}
adj_list[[1]].append(2)

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

A0

B1

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Appending to the wrong node's list.

Using a node number that does not exist in the dictionary.

To add an edge from node 1 to node 2, we append 2 to the list of node 1.

3fill in blank

hard

Fix the error in the adjacency matrix code to mark an edge between node 0 and node 2.

Data Structures Theory

adj_matrix = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
adj_matrix[0][[1]] = 1
adj_matrix[2][0] = 1

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

A2

B3

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong column index.

Confusing row and column indices.

To mark an edge from node 0 to node 2, set adj_matrix[0][2] = 1. The blank is the column index, which should be 2.

But since the code already sets adj_matrix[2][0] = 1, the blank must be 2 to complete the symmetric edge.

4fill in blank

hard

Fill both blanks to create an adjacency list entry for node 2 with edges to nodes 0 and 1.

Data Structures Theory

adj_list = {2: [[1], [2]]}

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

A0

B1

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Including the node itself (2) in its adjacency list.

Using nodes not connected to node 2.

Node 2 has edges to nodes 0 and 1, so the list should contain 0 and 1.

5fill in blank

hard

Fill both blanks to create a dictionary comprehension that builds an adjacency list for nodes with edges only if the node index is less than 3.

Data Structures Theory

adj_list = {i: [0 if j != i else 1 for j in range(5)] for i in range([1]) if i [2] 3}

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

A{

B5

C<

D[

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets instead of curly braces for dictionary comprehension.

Incorrect range or condition syntax.

The dictionary comprehension starts with '{'. The range for i is 5. The condition 'i < 3' filters nodes less than 3.