Yet Another Xinversion !

The problem statement is simple. You are given a rooted tree (1 is the root) and every node has a co…

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If you need help solving this problem, mention your approach and ask specific questions. Please avoid sharing your code and asking the Community to figure out “what’s wrong”.

I am getting a runtime error and I cannot for the life of me understand why it might be the case. Can someone help me?

class TreeNode: # creating a class to create a node

def __init__(self, value, cost):
    self.value = value
    self.children = []
    self.cost = cost
    self.parent = None

def add_child(self, child): # to add a child node
    child.parent = self

def add_cost(self, cost): # to do operation 1
    self.cost = cost

def xinverse(self): # to do operation 2
    count = 0
    for child in self.children:
        if child.cost > self.cost: # checks if child is valid
            count += 1
        count += child.xinverse() # repeats the process for the children of the child nodes
    # answer stored in the main variable count
    return count 

taking basic inputs and building the tree from the root node 1 up to the leaf nodes

N, Q = map(int, input().split(’ ‘))
costs = list(map(int, input().split(’ ')))

for n in range(N):
vars()[f’node_{n+1}'] = TreeNode(n+1, costs[n])

for i in range(N-1):
inp_objects = list(map(int, input().split(’ ‘)))
if inp_objects[0] < inp_objects[1]:

answers =
for q in range(Q):
command = list(map(int, input().split(’ ‘)))
if command[0] == 1: