improved solution for IterablesandIterators

Author: hernandanielg

Itertools/IterablesandIterators.py

@@ -5,16 +5,17 @@
 Author    : Ahmedur Rahman Shovon
 Created   : 15 July 2016
 '''
-import itertools
+from itertools import *
+
 n = int(input())
-s_ar = input().strip().split()
-s = ''.join(s_ar)
+s = str(input())
 k = int(input())
-combination = list(itertools.combinations(s,k))
-combination_count = len(combination)
-a_count = 0
 
-for single_combination in combination:
-    if 'a' in single_combination:
-        a_count += 1
-print(a_count / combination_count)
+pairs = list(combinations(s.split(),k))
+count = 0
+
+for pair in pairs:
+    if 'a' in pair:
+            count += 1
+
+print(count/len(pairs))