$**$This is the third time asking for help, but still not working. Please kindly help$**$

$[92]$ def find$\_$all$\_$nodes$\_$in$\_$cycle$($g$)$:

set$\_$of$\_$nodes $=$ set$()$ # This will store nodes that are part of any cycle

visited $=$ set$()$ # To keep track of visited nodes

parent $=$ dict$()$ # TO keep track of the parent of each node in the DFS treedef dfs$($node$,$ parent$\_$node$=$None$)$:

visited.add$($node$)$ # Mark node as visited

parent$[$node$]=$ parent$\_$node # Set the parent of the current nodefor neighbor in g$.$adj$\_$list$[$node$]$:

if neighbor not in visited:dfs$($neighbor$,$ node$)$

elif neighbor $!=$ parent$\_$node:cycle$\_$node $=$ node

cycle$\_$path $=[$cycle$\_$node$]$while cycle$\_$node $!=$ neighbor:

cycle$\_$node $=$ parent$[$cycle$\_$node$]$

cycle$\_$path.append$($cycle$\_$node$)$

set$\_$of$\_$nodes.update$($cycle$\_$path$)$ # Add all nodes in the cycle to the setfor node in range$($g$.$n$)$:

if node not in visited:dfs$($node$)$

return set$\_$of$\_$nodes # Return the set of nodes that are in cycles

#this is the example that we had for the problem.

g$3=$ UndirectedGraph$(8)$

g$3.$add$\_$edge$(0,1)$

g$3.$add$\_$edge$(0,2)$

g$3.$add$\_$edge$(0,4)$

g$3.$add$\_$edge$(2,3)$

g$3.$add$\_$edge$(2,4)$

g$3.$add$\_$edge$(3,4)$

g$3.$add$\_$edge$(5,6)$

g$3.$add$\_$edge$(5,7)$

s$\}=\backslash$mathrm$\{$ find all nodes in cycle$($g$3)$

print$($f$\text{'}$Your code returns set of nodes: $\{$s$\}\text{'})$

assert s $==\{0,2,3,4\},$ 'Fail: Set of nodes must be $\{0,2,3,4\}.\text{'}$g$3.$add$\_$edge$(6,7)$

s$1=$ find$\_$all$\_$nodes$\_$in$\_$cycle$($g$3)$

print$($f$\text{'}$Your code returns set of nodes: $\{$s$1\}\text{'})$

assert s$1==\{0,2,3,4,5,6,7\},$ 'Fail: Set of nodes must be $\{0,2,3,4,5,6,7\}.\text{'}$

print$(\text{'}$All tests passedd: $10$ points!$\text{'})$

$7$

KeyError Traceback $($most recent call last$)$

$20,21,--22,>indfs(node,paren{t}_n$ode$)$

$20,$ # Trace back using the parent nodes $to$ find all nodes $in$ the cycle

$21,$ while $cycl{e}_n$ode $$ neighbor:

$--22,cycl{e}_n$ode $=$ parent$[cycl{e}_n$ode$]$

$23cycl{e}_p$ath.append$(cycl{e}_n$ode$)$

$24se{t}_o{f}_n$odes.update$(cycl{e}_p$ath$)$ #Add all nodes $in$ the cycle $to$ the set