DFS Depth First Search on Graph in DSA Typescript - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start DFS from the given node.

DSA Typescript

function dfs(graph: Record<string, string[]>, node: string, visited: Set<string>) {
  if (visited.has(node)) return;
  visited.add(node);
  console.log(node);
  for (const neighbor of graph[node]) {
    dfs(graph, [1], visited);
  }
}

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Anode

Bneighbor

Cvisited

Dgraph

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the current node again instead of the neighbor.

Passing the visited set incorrectly.

Passing the whole graph instead of a node.

The DFS function should call itself recursively on each neighbor of the current node.

2fill in blank

medium

Complete the code to check if a node has been visited before processing it.

DSA Typescript

function dfs(graph: Record<string, string[]>, node: string, visited: Set<string>) {
  if ([1]) return;
  visited.add(node);
  console.log(node);
  for (const neighbor of graph[node]) {
    dfs(graph, neighbor, visited);
  }
}

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Avisited.contains(node)

Bnode in visited

Cvisited.has(node)

Dvisited.includes(node)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'in' operator which doesn't work for Set.

Using contains or includes which are not Set methods.

The Set method to check if an element exists is has().

3fill in blank

hard

Fix the error in the DFS function to avoid infinite recursion.

DSA Typescript

function dfs(graph: Record<string, string[]>, node: string, visited: Set<string>) {
  if (visited.has(node)) return;
  visited.add(node);
  console.log(node);
  for (const neighbor of graph[node]) {
    dfs(graph, neighbor, [1]);
  }
}

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Avisited

Bnew Set()

Cnew Set([node])

Dundefined

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a new Set() causes infinite recursion.

Passing undefined causes runtime errors.

The same visited set must be passed to keep track of visited nodes and prevent infinite loops.

4fill in blank

hard

Fill both blanks to create a DFS function that returns all visited nodes as an array.

DSA Typescript

function dfs(graph: Record<string, string[]>, node: string, visited: Set<string>, result: string[]) {
  if ([1]) return;
  visited.add(node);
  result.push(node);
  for (const neighbor of graph[node]) {
    dfs(graph, neighbor, visited, [2]);
  }
  return result;
}

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Avisited.has(node)

Bresult

Cvisited

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Passing visited instead of result to recursive calls.

Not checking if node is visited before processing.

Check if node is visited with visited.has(node) and pass the result array to recursive calls to collect nodes.

5fill in blank

hard

Fill all three blanks to implement DFS that returns nodes in order visited, avoiding cycles.

DSA Typescript

function dfs(graph: Record<string, string[]>, node: string, visited: Set<string> = new Set(), result: string[] = []) {
  if ([1]) return result;
  visited.add(node);
  result.push(node);
  for (const neighbor of graph[node]) {
    dfs(graph, [2], visited, [3]);
  }
  return result;
}

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

Avisited.has(node)

Bneighbor

Cresult

Dnode

Attempts:

3 left

💡 Hint

Common Mistakes

Using node instead of neighbor in recursive call.

Not passing the result array causing incomplete results.

Check if node is visited with visited.has(node), recurse on neighbor, and pass the result array to collect visited nodes.