261. Graph Valid Tree

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

, and 
edges = [[0,1], [0,2], [0,3], [1,4]]

Output:

 true

Example 2:

Input:

 
n = 5, 

and 
edges = [[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 .