Adjacency List Representation in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the adjacency list array for a graph with MAX_VERTICES vertices.

DSA C

struct Node* adjacencyList[[1]];

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AMAX_VERTICES

BMAX_EDGES

CMAX_NODES

DMAX_GRAPH

Attempts:

3 left

💡 Hint

Common Mistakes

Using the number of edges instead of vertices for the array size.

Using an undefined constant like MAX_NODES.

The adjacency list is an array where each index represents a vertex. The size should be the number of vertices, so MAX_VERTICES is correct.

2fill in blank

medium

Complete the code to create a new node for the adjacency list with the given vertex value.

DSA C

struct Node* newNode = (struct Node*)malloc(sizeof(struct [1]));
newNode->vertex = vertex;
newNode->next = NULL;

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AList

BNode

CGraph

DEdge

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong struct name like Graph or Edge.

Forgetting to cast the malloc result.

The node structure is named Node, so we allocate memory for struct Node.

3fill in blank

hard

Fix the error in the code that adds an edge from source to destination in the adjacency list.

DSA C

newNode->next = adjacencyList[[1]];
adjacencyList[source] = newNode;

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Asource

Bdestination

Cvertex

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Using destination as the index instead of source.

Using an undefined variable like vertex or node.

We insert the new node at the head of the list for the source vertex, so the index should be source.

4fill in blank

hard

Fill both blanks to complete the function that prints the adjacency list of the graph.

DSA C

for (int i = 0; i < [1]; i++) {
    struct Node* temp = adjacencyList[i];
    printf("Vertex %d:", i);
    while (temp != [2]) {
        printf(" -> %d", temp->vertex);
        temp = temp->next;
    }
    printf("\n");
}

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AMAX_VERTICES

BNULL

C0

DNULLPTR

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 instead of MAX_VERTICES for the loop limit.

Using NULLPTR which is not standard in C.

The loop runs from 0 to MAX_VERTICES to cover all vertices. The end of the linked list is marked by NULL.

5fill in blank

hard

Fill all three blanks to complete the function that adds an undirected edge between two vertices.

DSA C

void addEdge(int src, int dest) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct [1]));
    newNode->vertex = dest;
    newNode->next = adjacencyList[src];
    adjacencyList[src] = newNode;

    newNode = (struct Node*)malloc(sizeof(struct [2]));
    newNode->vertex = src;
    newNode->next = adjacencyList[[3]];
    adjacencyList[dest] = newNode;
}

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ANode

BGraph

Csrc

Ddest

Attempts:

3 left

💡 Hint

Common Mistakes

Using Graph instead of Node for malloc size.

Using src instead of dest for the second adjacency list index.

Both nodes are of type Node. The second new node is added to the adjacency list of dest, so the index is dest.