Adjacency List vs Matrix When to Choose Which in DSA C - Interactive Comparison Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an adjacency matrix for a graph with 5 vertices.

DSA C

int graph[5][5] = [1];

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

A{{5}}

B{{1}}

C{{-1}}

D{{0}}

Attempts:

3 left

💡 Hint

Common Mistakes

Using 1 instead of 0 initializes all edges as present.

Using -1 is invalid for adjacency matrix initialization.

The adjacency matrix is initialized with zeros to indicate no edges initially.

2fill in blank

medium

Complete the code to add an edge from vertex 2 to vertex 4 in an adjacency matrix.

DSA C

graph[2][[1]] = 1;

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A4

B3

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 5 causes out-of-bounds error.

Using index 3 adds edge to wrong vertex.

Vertices are zero-indexed, so vertex 4 corresponds to index 4.

3fill in blank

hard

Fix the error in the adjacency list insertion code to add vertex 3 to vertex 1's list.

DSA C

adjList[1].push_back([1]);

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A3

B1

C0

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Pushing the source vertex instead of the destination.

Using an invalid vertex index.

To add an edge from vertex 1 to vertex 3, push 3 into vertex 1's adjacency list.

4fill in blank

hard

Fill both blanks to create an adjacency list for a graph with 4 vertices.

DSA C

std::vector<int> adjList[[1]];

adjList[0].push_back([2]);

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A4

B3

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong size for adjacency list array.

Pushing incorrect vertex number.

The graph has 4 vertices, so the array size is 4. Adding an edge from vertex 0 to vertex 1 means pushing 1 into adjList[0].

5fill in blank

hard

Fill all three blanks to check if an edge exists from vertex 2 to vertex 3 in an adjacency matrix.

DSA C

if (graph[[1]][[2]] [3] 1) {
    printf("Edge exists\n");
}

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

A2

B3

C==

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong indices for vertices.

Using '!=' instead of '==' causing wrong condition.

Check the matrix at row 2, column 3. If the value equals 1, the edge exists.