subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226

git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208
git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789

1 files changed, 26 insertions, 0 deletions

diff --git a/users/wpcarro/scratch/facebook/linked-list-cycles.py b/users/wpcarro/scratch/facebook/linked-list-cycles.py
new file mode 100644
index 000000000000..56f54d497808
--- /dev/null
+++ b/users/wpcarro/scratch/facebook/linked-list-cycles.py
@@ -0,0 +1,26 @@
+import random
+
+from linked_list import Node
+
+def contains_cycle(node):
+    one = node
+    two = node
+    while two.next and two.next.next:
+        one = one.next
+        two = two.next.next
+        if one == two:
+            return True
+    return False
+
+xs = Node(1, Node(2, Node(3)))
+assert not contains_cycle(xs)
+print("Success!")
+
+a = Node(1)
+b = Node(2)
+c = Node(3)
+a.next = b
+b.next = c
+c.next = random.choice([a, b, c])
+assert contains_cycle(a)
+print("Success!")