Graph Valid Tree Check

Problem

Decide whether an undirected graph with n nodes and the given edges is a valid tree.

A graph is a tree when it is connected and acyclic, which for n nodes is equivalent to having exactly n - 1 edges and no cycle. edges is a list of [u, v] pairs.

Hint

n - 1 edges plus no cycle implies connectivity.

Test cases

case 1

in: [5,[[0,1],[0,2],[0,3],[1,4]]]

expected: true

case 2

in: [5,[[0,1],[1,2],[2,3],[3,4],[4,0]]]

expected: false

case 3

in: [1,[]]

expected: true

case 4

in: [2,[]]

expected: false

case 5

in: [2,[[0,1]]]

expected: true

Starter codePython

def valid_tree(n, edges):
    # Your code here
    pass

5 test cases · run your code against them in the editor