Python: runtime error in Google Kickstart 2020 - Round A

Question

I'm trying for fun to solve problems for Google Kickstart 2020, Round A, using Python 3.7. I passed all the problems except the "Bundling" one. My algorithm passes the samples, but fails the tests with a runtime error. I tested it also with big test cases that I build with a simple script, and it works, without rising any type of exception.

I also thought that, since I'm using Python 3.8 on my machine, while Google tests the scripts with 3.7, this could be the point... but I cant' find anything of wrong in my code. Here is my code:

ans = 0
class Node:
    def __init__(self):
        self.children = {}
        self.count = 0
    
    def insert(node, key):
        for char in key:
            idx = char
            if idx not in node.children:
                node.children[idx] = Node()
            node = node.children[idx]
            
        node.count +=1

    def resetAns(self):
        global ans
        ans = 0

    def dfs(self, dep=0, k=0):
        global ans
        for c in self.children:
            self.children[c].dfs(dep+1, k)
            self.count+=self.children[c].count
        while self.count >= k:
            self.count -= k
            ans+=dep
        return ans

def bundling():
    N, K = map(int, input().split())
    _node = Node()
    _node.resetAns()
    for _ in range(0, N):
        _v = input()
        _node.insert(_v)
    return _node.dfs(0, K)            

for _ in range(int(input())):
    print("Case #{}: {}".format(_, bundling()))

Any help is welcome :D

Answer 1

The problem has occurred because of the small default recursion depth limit python provides. You can set the limit explicitly using the below code.

import sys 
sys.setrecursionlimit(10**6)