Interview Questions

BFS explores level by level using a queue — best for shortest path in unweighted graphs. DFS goes as deep as possible using a stack/recursion — useful for topological sort, cycle detection, and exploring all paths. Both are O(V+E).

Vertical scaling adds more power (CPU/RAM) to one machine — simple but capped and a single point of failure. Horizontal scaling adds more machines — more complex (load balancing, data partitioning) but elastic and fault-tolerant.