MCQs

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Overall MCQs for Reference

1. Which data structure is fundamental for implementing Breadth First Search (BFS)?
   a. Stack
   b. Queue
   c. Array
   d. Tree
   Answer: b. Queuecelerdata+1​
2. What is the main characteristic of BFS traversal?
   a. Depth-first exploration
   b. Level-wise exploration
   c. Random exploration
   d. Backtracking
   Answer: b. Level-wise explorationcodecademy+1​
3. What is the time complexity of Breadth First Search for a graph with V vertices and E edges?
   a. O(V)
   b. O(E)
   c. O(V + E)
   d. O(VE)
   Answer: c. O(V + E)geeksforgeeks+2​
4. In BFS, which nodes are explored first?
   a. Nodes farthest from the source
   b. Nodes at the same depth
   c. Nodes with maximum degree
   d. Leaf nodes
   Answer: b. Nodes at the same depthgeeksforgeeks+1​
5. Which type of graph does BFS guarantee the shortest path?
   a. Weighted graph
   b. Unweighted graph
   c. Directed graph
   d. Random graph
   Answer: b. Unweighted graphiquanta+1​
6. What is the space complexity of BFS in terms of the number of vertices (V)?
   a. O(V)
   b. O(E)
   c. O(1)
   d. O(log V)
   Answer: a. O(V)fiveable+1​
7. What happens if the BFS queue is empty?
   a. The traversal continues infinitely
   b. The algorithm terminates
   c. A stack overflow occurs
   d. The algorithm switches to DFS
   Answer: b. The algorithm terminatestutorialspoint+1​
8. Which condition causes BFS to revisit nodes?
   a. No visited set used
   b. Using a stack
   c. Infinite branching factor
   d. Backtracking enabled
   Answer: a. No visited set usedcelerdata+1​
9. BFS is especially useful in which area of machine learning or AI?
   a. Decision trees
   b. Feature selection
   c. Search algorithms
   d. Regularization
   Answer: c. Search algorithmsindiaai+1​
10. What is the typical application of BFS in social network analysis?
    a. Feature extraction
    b. Finding shortest connections
    c. Model training
    d. Encoding nodes as vectors
    Answer: b. Finding shortest connectionsiquanta​
11. Which data structure is NOT used in BFS?
    a. Stack
    b. Queue
    c. Visited set
    d. Adjacency list
    Answer: a. Stackgeeksforgeeks+1​
12. BFS can be used to check if a graph is:
    a. Cyclic
    b. Bipartite
    c. Weighted
    d. Directed
    Answer: b. Bipartitecelerdata​
13. What ensures BFS does not get trapped exploring a single path?
    a. Backtracking
    b. Level-wise approach
    c. Depth limit
    d. Heuristic function
    Answer: b. Level-wise approachgeeksforgeeks​
14. Which of the following is a disadvantage of BFS?
    a. Not guaranteed to find solution
    b. Can exhaust memory quickly
    c. Slow for unweighted graphs
    d. Ignores all branching factors
    Answer: b. Can exhaust memory quicklygeeksforgeeks​
15. The main difference between BFS and DFS is:
    a. BFS uses depth-first exploration
    b. DFS uses queue
    c. BFS uses level-wise exploration
    d. DFS finds shortest paths in unweighted graphs
    Answer: c. BFS uses level-wise explorationgeeksforgeeks​
16. In a binary tree, BFS corresponds to:
    a. Post-order traversal
    b. In-order traversal
    c. Level-order traversal
    d. Pre-order traversal
    Answer: c. Level-order traversalinterviewcake​
17. What is the primary use of the queue in BFS?
    a. To reverse node order
    b. To delay node visits
    c. To explore nodes FIFO
    d. To store only leaf nodes
    Answer: c. To explore nodes FIFOcodecademy+1​
18. BFS terminates when:
    a. All nodes are visited
    b. All edges are weighted
    c. The stack is empty
    d. Nodes exceed branching factor
    Answer: a. All nodes are visitedtutorialspoint​
19. BFS is preferred over DFS when:
    a. Searching for deepest solution
    b. Searching for shortest path
    c. Memory is limited
    d. Algorithm speed is priority
    Answer: b. Searching for shortest pathgeeksforgeeks​
20. What is explored after all immediate neighbors in BFS?
    a. Deepest descendants
    b. Next level neighbors
    c. Only back edges
    d. Random nodes
    Answer: b. Next level neighborsgeeksforgeeks+1​
21. Which scenario best suits BFS in AI search?
    a. Weighted graph routing
    b. Pathfinding in unweighted maze
    c. Feature vector calculation
    d. Tree pruning
    Answer: b. Pathfinding in unweighted mazeinterviewcake​
22. What is the main reason BFS is space-intensive?
    a. It saves all paths
    b. It must store all nodes at a given level
    c. It discards visited nodes
    d. It prioritizes leaf nodes
    Answer: b. It must store all nodes at a given levelgeeksforgeeks​
23. Which variant of BFS is often used for minimum spanning trees?
    a. Modified DFS
    b. Prim’s algorithm
    c. Backtracking
    d. A* search
    Answer: b. Prim’s algorithmcelerdata​
24. In web crawling, BFS ensures:
    a. All links are indexed randomly
    b. Each page is indexed before deeper links
    c. Only root URLs are indexed
    d. Edges are ignored
    Answer: b. Each page is indexed before deeper linksiquanta​
25. For an unweighted graph, BFS starts at the source and:
    a. Jumps to leaf nodes
    b. Explores all reachable nodes level by level
    c. Marks only non-neighbors as visited
    d. Uses heuristic function
    Answer: b. Explores all reachable nodes level by levelgeeksforgeeks+1​
26. If a node has multiple neighbors, BFS will:
    a. Visit all at same depth before proceeding
    b. Randomly select one neighbor
    c. Use heuristic to guide traversal
    d. Skip redundant nodes
    Answer: a. Visit all at same depth before proceedingtutorialspoint+1​
27. Which is true for BFS in infinite graphs?
    a. Always finds a solution
    b. May run indefinitely
    c. Guaranteed optimality
    d. Finds shortest weighted path
    Answer: b. May run indefinitelygeeksforgeeks​
28. BFS is optimal for:
    a. Unweighted graphs only
    b. Weighted graphs only
    c. Cyclic graphs only
    d. Trees only
    Answer: a. Unweighted graphs onlygeeksforgeeks+1​
29. The branching factor in BFS affects:
    a. Only the speed
    b. Memory usage
    c. Only output format
    d. The number of levels traversed
    Answer: b. Memory usagegeeksforgeeks​
30. Which step belongs to BFS algorithm?
    a. Use stack for node storage
    b. Mark source as visited
    c. Remove node from visited set
    d. Start traversal from leaf node
    Answer: b. Mark source as visitedcodecademy+1​
31. What would happen if a cyclic graph is traversed with BFS without a visited set?
    a. All nodes are explored once
    b. Some nodes are explored multiple times
    c. Only unconnected nodes are visited
    d. No traversal occurs
    Answer: b. Some nodes are explored multiple timescodecademy+1​
32. BFS is essential for which feature in search engines?
    a. Feature extraction
    b. Indexing web pages systematically
    c. Hyperlink detection
    d. Ranking algorithms
    Answer: b. Indexing web pages systematicallyiquanta​
33. What type of traversal does BFS follow?
    a. Branch-first traversal
    b. Level-by-level traversal
    c. Depth-first traversal
    d. Random traversal
    Answer: b. Level-by-level traversalcodecademy+1​
34. Which step is NOT part of the BFS process?
    a. Dequeue node for processing
    b. Enqueue all unvisited neighbors
    c. Ignore next level completely
    d. Mark nodes as visited
    Answer: c. Ignore next level completelytutorialspoint+1​
35. For a tree of depth ‘d’ and branching factor ‘b’, maximum nodes at the deepest level are:
    a. b^d
    b. b/d
    c. d/b
    d. d^b
    Answer: a. b^dgeeksforgeeks​
36. What is the role of the adjacency list in BFS?
    a. Store heap values
    b. Determine neighbors to visit
    c. Prevent duplicate entries
    d. Facilitate stack operations
    Answer: b. Determine neighbors to visitthealgorists​
37. When can BFS use less memory than DFS?
    a. When the graph is sparse
    b. Never
    c. On deep graphs
    d. When branching factor is small
    Answer: d. When branching factor is smallgeeksforgeeks+1​
38. BFS does not backtrack because:
    a. It stores only source nodes
    b. Each node is visited only once
    c. It uses FIFO queue
    d. It uses LIFO stack
    Answer: c. It uses FIFO queuegeeksforgeeks​
39. BFS finds:
    a. Longest path in weighted graph
    b. Shortest path in unweighted graph
    c. Shortest path in weighted graph
    d. All possible cycles
    Answer: b. Shortest path in unweighted graphcelerdata+1​
40. Which feature makes BFS easy to implement in most programming languages?
    a. Recursion-based traversal
    b. Queue-based approach
    c. Matrix storage
    d. Depth limit parameter
    Answer: b. Queue-based approachtutorialspoint+1​
41. BFS is complete, meaning:
    a. Will exhaust all paths if necessary
    b. May miss some nodes
    c. Will terminate if queue runs out
    d. Never terminates on finite graphs
    Answer: a. Will exhaust all paths if necessarygeeksforgeeks+1​
42. BFS is not suitable for:
    a. Searching wide shallow graphs
    b. Finding solutions deep in search space
    c. Web crawling
    d. Peer-to-peer networks
    Answer: b. Finding solutions deep in search spacegeeksforgeeks+1​
43. Which step enhances cycle detection in BFS?
    a. Skipping visited nodes
    b. Enqueuing all nodes
    c. Restarting from leaf nodes
    d. Ignoring edge weights
    Answer: a. Skipping visited nodescelerdata+1​
44. What is a potential real-world application for BFS?
    a. Analyzing social network connections
    b. Generating hash values
    c. Minimizing loss in neural networks
    d. Training supervised models
    Answer: a. Analyzing social network connectionsiquanta​
45. Which makes BFS an uninformed (blind) search?
    a. Uses only connectivity, no heuristics
    b. Always finds shortest path
    c. Requires weighted edges
    d. Relies on depth level
    Answer: a. Uses only connectivity, no heuristicsgeeksforgeeks​
46. What is the first node to be explored in BFS given a starting vertex?
    a. The deepest node in the graph
    b. The starting node itself
    c. Any unvisited node
    d. The last node alphabetically
    Answer: b. The starting node itselfcodecademy+1​
47. Which of these is commonly added to BFS implementation for practical efficiency?
    a. Hash table for visited nodes
    b. Recursion function
    c. Stack overflow detection
    d. Unweighted edge list
    Answer: a. Hash table for visited nodescelerdata+1​
48. In graph databases, BFS can be used to:
    a. Traverse relationships level-wise
    b. Build feature vectors
    c. Index tables recursively
    d. Encrypt data traffic
    Answer: a. Traverse relationships level-wiseiquanta+1​
49. What is the final outcome if BFS explores all nodes in a connected graph?
    a. Only one path found
    b. All nodes visited at least once
    c. Some nodes are skipped
    d. End node always at maximum depth
    Answer: b. All nodes visited at least oncetutorialspoint+1​
50. Which property distinguishes BFS from depth-limited search?
    a. Guaranteed optimal solution
    b. Limited exploration depth
    c. Stack-based implementation
    d. Underground backtracking
    Answer: a. Guaranteed optimal solutiongeeksforgeeks+1​

1. https://celerdata.com/glossary/breadth-first-search-bfs
2. https://www.geeksforgeeks.org/dsa/difference-between-bfs-and-dfs/
3. https://www.codecademy.com/article/breadth-first-search-bfs-algorithm
4. https://www.geeksforgeeks.org/dsa/time-and-space-complexity-of-breadth-first-search-bfs/
5. https://fiveable.me/data-structures/unit-11/breadth-first-search-bfs-algorithm/study-guide/3ykxmer0DnvoLRNV
6. https://www.thealgorists.com/Algo/GraphTheory/BFS
7. https://www.geeksforgeeks.org/artificial-intelligence/breadth-first-search-bfs-for-artificial-intelligence/
8. https://www.iquanta.in/blog/applications-of-bfs-or-breadth-first-search/
9. https://www.tutorialspoint.com/data_structures_algorithms/breadth_first_traversal.htm
10. https://indiaai.gov.in/article/understanding-breadth-first-search
11. https://www.geeksforgeeks.org/dsa/applications-of-breadth-first-traversal/
12. https://www.interviewcake.com/concept/java/bfs
13. https://www.geeksforgeeks.org/artificial-intelligence/difference-between-depth-first-search-breadth-first-search-and-depth-limit-search-in-ai/
14. https://www.geeksforgeeks.org/dsa/breadth-first-search-or-bfs-for-a-graph/
15. https://en.wikipedia.org/wiki/Breadth-first_search
16. https://www.edureka.co/blog/breadth-first-search-algorithm/
17. https://vtupulse.com/artificial-intelligence/breadth-first-search-example-advantages-and-disadvantages/
18. https://interviewing.io/breadth-first-search-interview-questions
19. https://www.youtube.com/watch?v=qul0f79gxGs
20. https://www.linkedin.com/pulse/dfs-bfs-coding-interview-3-steps-success-jimmy-zhang-hldgf