Challenge: Implement Breadth-First Search

Statement

Given a directed graph represented as an adjacency list, graph, and an integer, source, which is the starting vertex number, return an array of integers, result, that contains the order of the graph’s breadth-first traversal starting from the source vertex.

Constraints:

• $1$ $\leq$graph.length $\leq$$10^3$

• $-1000$ $\leq$graph[i][j] $\leq$$1000$

Examples