Breadth First Search

Breadth First search is an effective search mechanism for Graphs and Tree Data structure. As the name suggest, this technique makes sure that all the nodes at same level/ breadth are checked before moving to deeper levels.


The above structure is hybrid of tree and graph (Still a tree as there are no cycles). Let us what it means to do a breadth first search here.

We will start with root node i.e. 10.

Move to level 2 and check nodes 18, 22, 5.

Check the next level- 7, 15, 12 and so on.

Here is algorithm to implement Breadth first search

1. Add root node R to queue- Q

2. Fetch next node N from Q

3 a. If the N.val is required val, return success

3 b. Else Find all Child/ Neighbour nodes which are not traversed already and add to Queue

4. If there are more nodes in Q, Repeat from 2.

5. If Q is empty, we know we have traversed all nodes, return failure as node not found

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