Shortest Path Between A and B
Prereq: BFS on Graph
Given an (unweighted) connected graph, return the length of the shortest path between two nodes A and B, in terms of the number of edges.
Assume there always exists a path between nodes A and B.
Input:
graph = [[1, 2], [0, 2, 3], [0, 1], [1]] A = 0 B = 3
Output: 2
Note that the graph is given as a 2-d list, where graph[i] is the list of nodes that node i is adjacent to.
You can use the BFS template from BFS on Graphs as your starter code.