Adjacency Matrix Representation in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a 2D adjacency matrix for 4 vertices.

DSA C

int adjacencyMatrix[4][4] = [1];

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A{{0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}, {0, 0, 0, 0}}

B{{0}}

C0

DNULL

Attempts:

3 left

💡 Hint

Common Mistakes

Using a single zero instead of a 2D array initializer.

Using NULL which is invalid for integer arrays.

The adjacency matrix is a 2D array initialized with zeros for no edges.

2fill in blank

medium

Complete the code to add an edge from vertex 1 to vertex 3 in the adjacency matrix.

DSA C

adjacencyMatrix[1][[1]] = 1;

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A2

B3

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 3 as index which is out of bounds for vertex 3.

Confusing vertex numbers with array indices.

Index 2 represents vertex 3 because indexing starts at 0.

3fill in blank

hard

Fix the error in the code to correctly check if there is an edge from vertex 2 to vertex 0.

DSA C

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

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A3

B2

C1

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using vertex number directly as index without subtracting 1.

Using an index out of bounds like 3.

Vertex 0 corresponds to index 0 in the matrix.

4fill in blank

hard

Fill both blanks to complete the nested loops that print the adjacency matrix.

DSA C

for (int i = 0; i [1] 4; i++) {
    for (int j = 0; j [2] 4; j++) {
        printf("%d ", adjacencyMatrix[i][j]);
    }
    printf("\n");
}

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A<

B<=

C>

D>=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<=' causes out of bounds access.

Using '>' or '>=' causes loops not to run.

Loop indices run from 0 to less than 4 to cover all vertices.

5fill in blank

hard

Fill all three blanks to create a function that initializes the adjacency matrix to zero.

DSA C

void initializeMatrix(int matrix[4][4]) {
    for (int [1] = 0; [2] < 4; [3]++) {
        for (int j = 0; j < 4; j++) {
            matrix[i][j] = 0;
        }
    }
}

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Ai

Ci++

Dj

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'j' in outer loop which conflicts with inner loop.

Missing increment expression causes infinite loop.

The outer loop uses variable i starting at 0 and increments by 1 until less than 4.