Enter your code here. Read input from STDIN. Print output to STDOUT

import itertools N = int(input()) letters = input().split() k = int(input()) listed_combinations = list(itertools.combinations(letters,k))

count = 0

for i in listed_combinations: if "a" in i: count +=1

print(count/len(listed_combinations))

from itertools import combinations

Reading input

n = int(input())

letters = input().split()

k = int(input())

Finding the indices where the letter 'a' occurs

a_indices = [i for i, letter in enumerate(letters) if letter == 'a']

Generating all combinations of k indices from the list

total_combinations = list(combinations(range(n), k))

Counting the combinations that contain at least one 'a' index

favorable_combinations = [ combo for combo in total_combinations if any(i in a_indices for i in combo) ]

Calculating the probability

probability = len(favorable_combinations) / len(total_combinations)

Printing the result with 4 decimal places print(f"{probability:.4f}")

import itertools

n = int(input())

letters = input().split()

k = int(input())

count = letters.count('a')

total_combinations = len(list(itertools.combinations(range(n),k)))

favorable_combinations = 0

for comb in itertools.combinations(range(n), k):

if any(letters[i] == 'a' for i in comb):
    favorable_combinations += 1

probability = favorable_combinations/total_combinations print(f"{probability:.4f}")

Please, can anybody answer me, why itertools.combinations() is fine, but interpreter cannot recognize itertools.ifilter()? I see that using sum with a list comprihension is easier, I used built in filter() with success, though.