subtree(users/wpcarro): docking briefcase at '24f5a642'

git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c
git-subtree-split: 24f5a642af
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789

users/wpcarro/scratch/facebook/moderate/rand7.py

@@ -0,0 +1,25 @@
+# Define a function, rand7, that generates a random number [0,7), using only
+# rand5, which generates a random number [0,5).
+
+import random
+from collections import Counter
+
+# Returns [0,4]
+def rand5():
+    return random.randint(0,4)
+
+# Return [0,6]
+def rand7_a():
+    return sum(rand5() for _ in range(7)) % 7
+
+# Return [0,6]
+def rand7_b():
+    x = 5 * rand5() + rand5()
+    if x < 21:
+        return x % 7
+    return rand7_b()
+
+c = Counter([rand7_a() for _ in range(100000)])
+print(c)
+c = Counter([rand7_b() for _ in range(100000)])
+print(c)