Challenge: Implement Breadth First Graph Traversal

Problem Statement

You have to implement the Breadth-First Traversal in C++.

Input

A graph represented as an adjacency list and a starting vertex.

Output

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

Sample Input

Graph:

graph = {0 -> 1
         1 -> 2
         1 -> 3
         2 -> 4
         3 -> 4
         3 -> 5}

Sample Output

"0 1 2 3 4 5"; 

Print Left Child first and then Right Child!