Challenge: Implement Breadth First Search

Problem Statement

In this exercise, you have to implement Breadth First Search traversal in Java. It is a level-by-level searching algorithm for the graph, so we are going to use our already-implemented class of Graph for this task (since we have already covered the implementation of Graph).

Note: Your solution should work for both connected and unconnected graphs. For an unconnected graph, the order of output should depend upon indices in ascending order.

To solve this problem, all the previously implemented data structures will be available to us.

Input

A graph in the form of an adjacency list

Output

A string containing the vertices of the graph listed in the correct order of traversal.

Sample Input

Graph:

Vertex	Edges
0	1, 2
1	3, 4
2	None
3	None
4	None

In the Input column of Test cases, this graph will be represented as: |V|=5, E:[(0,1)(0,2)(1,3)(1,4)], where, |V| represents the number of vertices while E represents the edges.

Sample Output

"01234"

and

"02143"