Add all the A tasks

Task/Average-loop-length/Python/average-loop-length.py

@@ -0,0 +1,27 @@
+from __future__ import division # Only necessary for Python 2.X
+from math import factorial
+from random import randrange
+
+MAX_N = 20
+TIMES = 1000000
+
+def analytical(n):
+	return sum(factorial(n) / pow(n, i) / factorial(n -i) for i in range(1, n+1))
+
+def test(n, times):
+    count = 0
+    for i in range(times):
+        x, bits = 1, 0
+        while not (bits & x):
+            count += 1
+            bits |= x
+            x = 1 << randrange(n)
+    return count / times
+
+if __name__ == '__main__':
+    print(" n\tavg\texp.\tdiff\n-------------------------------")
+    for n in range(1, MAX_N+1):
+        avg = test(n, TIMES)
+        theory = analytical(n)
+        diff = (avg / theory - 1) * 100
+        print("%2d %8.4f %8.4f %6.3f%%" % (n, avg, theory, diff))