Cycle Detection Undirected

Problem

Decide whether an undirected graph with n nodes contains a cycle.

Self-loops and parallel edges (the same pair listed twice) both count as cycles. edges is a list of [u, v] pairs.

Hint

An edge whose endpoints already share a root closes a cycle.

case 1

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

expected: false

case 2

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

expected: true

case 3

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

expected: true

case 4

in: [1,[]]

expected: false

case 5

in: [3,[[0,0]]]

expected: true

Starter codePython

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

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