### Depth-First Search (DFS) vs Breadth-First Search (BFS)

In this post, we will learn the difference between Depth-First Search (DFS) and Breadth-First Search (BFS) in Java. This is a frequently asked question in Java interviews for beginners. Let's dive into it.

## Difference between Depth-First Search (DFS) and Breadth-First Search (BFS) in Java

Feature Depth-First Search (DFS) Breadth-First Search (BFS)
Approach DFS explores as far as possible along each branch before backtracking. BFS explores all the nodes at the current depth level before moving to the next depth level.
Data Structure DFS is typically implemented using a stack (either explicitly or implicitly using recursion). BFS is typically implemented using a queue.
Order of Exploration DFS explores nodes in the order they are encountered along each branch. BFS explores nodes level by level, visiting all nodes at the current level before moving to the next level.
Completeness DFS may not necessarily explore all nodes in the graph. It may get stuck in an infinite loop in cyclic graphs. BFS always explores all nodes in the graph, ensuring completeness.
Memory Usage DFS typically uses less memory compared to BFS, as it explores deeply before backtracking. BFS uses more memory as it needs to store all nodes at the current level before moving to the next level.
Applications DFS is often used for pathfinding, topological sorting, and graph traversal problems. BFS is used for shortest path finding, finding connected components, and exploring all possible states in a state space.
Time Complexity (for a graph with V vertices and E edges) In general, DFS has a time complexity of O(V + E). However, it can vary based on the graph structure and the implementation used. BFS has a time complexity of O(V + E), as it visits all vertices and edges in the graph once.
Example  In summary, DFS explores as far as possible along each branch before backtracking, while BFS explores all nodes at the current depth level before moving to the next level. The choice between DFS and BFS depends on the specific problem and the characteristics of the graph or data structure being traversed.