breadth first search and best first search



Breadth first search (BFS) is an algorithm for traversing or searching tree or graph data structures. It starts at the tree root (or some arbitrary node of a graph, sometimes referred to as a 'search key') and explores all of the neighbor nodes at the present depth prior to moving on to the nodes at the next depth level.


Here is an example of how BFS works:


Let's say we have a graph with the following nodes:


A

B

C

D

E

F

G

H


If we start at node A and perform a breadth first search, we will visit the nodes in the following order:


A

B

C

D

E

F

G

H


As you can see, BFS explores the nodes in a level-order fashion. This means that it starts at the root node and then explores all of the nodes at the next level, and so on.


Best First Search (BFS)
Best first search (BFS) is an algorithm for finding the shortest path between two nodes in a graph. It works by maintaining a priority queue of nodes to be explored, and always exploring the node with the lowest estimated cost to the goal.


Here is an example of how BFS works:


Let's say we have a graph with the following nodes:


A

B

C

D

E

F

G

H


The cost of each edge in the graph is shown below:


A to B = 1

A to C = 2

A to D = 3

B to E = 1

B to F = 2

C to G = 1

C to H = 2


If we start at node A and perform a best first search, we will find the shortest path to node H, which is A -> C -> H.


As you can see, BFS explores the nodes in a way that minimizes the cost of the path to the goal. This makes it a very efficient algorithm for finding the shortest path between two nodes in a graph.


Comparison of BFS and BFS


BFS and BFS are both powerful algorithms for traversing and searching graphs. However, they have different strengths and weaknesses.


BFS is a good choice for problems where you need to explore all of the nodes in a graph. It is also a good choice for problems where you need to find the shortest path between two nodes in a graph. However, BFS can be inefficient for problems where the graph is very large or where the nodes are not connected in a regular way.


BFS is a good choice for problems where you need to find the shortest path between two nodes in a graph. It is also a good choice for problems where the graph is very large or where the nodes are not connected in a regular way. However, BFS can be inefficient for problems where you need to explore all of the nodes in a graph.


Which algorithm should you use?


The best algorithm to use depends on the specific problem you are trying to solve. If you need to explore all of the nodes in a graph, then BFS is a good choice. If you need to find the shortest path between two nodes in a graph, then BFS is a good choice. However, if you need to find the shortest path between two nodes in a large or irregular graph, then BFS may not be the best choice.