Connected Components

Problem

Given n nodes labelled 0 to n-1 and undirected edges as [u, v] pairs, return the number of connected components including isolated nodes.

Use union-find to merge the endpoints of every edge, then count the distinct roots. Return 0 when n is 0.

Hint

Nodes with no edges are each their own component.

case 1

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

expected: 2

case 2

in: [5,[]]

expected: 5

case 3

in: [1,[]]

expected: 1

case 4

in: [0,[]]

expected: 0

case 5

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

expected: 1

Starter codePython

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

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