HackerRank Python - Iterables and Iterators

The itertools module standardizes a core set of fast, memory efficient tools that are useful by themselves or in combination. Together, they form an iterator algebra making it possible to construct specialized tools succinctly and efficiently in pure Python.

  1. # Enter your code here. Read input from STDIN. Print output to STDOUT
  2. from itertools import combinations
  3. n = int(input())
  4. array = input().split()
  5. k = int(input())
  6. comb_list = list(combinations(array, k))
  7. a_list = [e for e in comb_list if 'a' in e]
  8. print(len(a_list) / len(comb_list))

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