Given n nodes labeled from 0 to n-1 and a list of
undirected edges (each edge is a pair of nodes), write a function to check whether these
edges make up a valid tree.
Example 1:
Input:n = 5, andedges = [[0,1], [0,2], [0,3], [1,4]]Output: true
Example 2:
Input:n = 5,andedges = [[0,1], [1,2], [2,3], [1,3], [1,4]]Output: false
Note: you can assume that no duplicate edges will appear in edges. Since
all edges are undirected, [0,1] is the same as [1,0] and thus will
not appear together in edges.