Topological Sort Using DFS in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare the adjacency list for the graph.

DSA C

int adj[[1]][100]; // adjacency list for graph
int visited[100];

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A10

B50

C100

D200

Attempts:

3 left

💡 Hint

Common Mistakes

Using a size larger than the number of nodes wastes memory.

Using a smaller size causes out-of-bounds errors.

The graph size is set to 10 nodes, so the adjacency list should be declared with size 10.

2fill in blank

medium

Complete the DFS function header to accept the current node.

DSA C

void dfs(int [1]) {
    visited[node] = 1;
    // DFS logic
}

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Astart

Bnode

Cindex

Dcurrent

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter name that doesn't match the variable used inside the function.

The parameter name 'node' clearly represents the current node in DFS traversal.

3fill in blank

hard

Fix the error in the DFS recursive call to visit adjacent nodes.

DSA C

for (int i = 0; i < adj[node][0]; i++) {
    int adjNode = adj[node][i + 1];
    if (!visited[adjNode]) {
        dfs([1]);
    }
}

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AadjNode

Bi

Cnode

Dvisited

Attempts:

3 left

💡 Hint

Common Mistakes

Calling dfs on the loop index 'i' instead of the adjacent node.

Calling dfs on the current node again causing infinite recursion.

The DFS should be called on the adjacent node, which is 'adjNode'.

4fill in blank

hard

Fill both blanks to push the node onto the stack after visiting all neighbors.

DSA C

void dfs(int node) {
    visited[node] = 1;
    for (int i = 0; i < adj[node][0]; i++) {
        int adjNode = adj[node][i + 1];
        if (!visited[adjNode]) {
            dfs(adjNode);
        }
    }
    stack[[1]] = node;
    [2]++;
}

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Atop

Bcount

Cindex

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variables for index and increment causing errors.

Forgetting to increment the stack pointer.

The variable 'top' is used as the stack pointer to store nodes and increment after pushing.

5fill in blank

hard

Fill all three blanks to print the topological order from the stack.

DSA C

for (int i = [1] - 1; i >= 0; i--) {
    printf("%d ", stack[[2]]);
}
printf("\n");

// Reset stack pointer
[3] = 0;

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Atop

Bi

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong variable names causing compilation errors.

Not resetting the stack pointer after printing.

We start from 'top - 1' down to 0, print stack[i], and reset 'top' to 0 after printing.