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, 22 insertions, 0 deletions

diff --git a/users/wpcarro/scratch/facebook/find-duplicate-optimize-for-space.py b/users/wpcarro/scratch/facebook/find-duplicate-optimize-for-space.py
new file mode 100644
index 000000000000..7c491aef604e
--- /dev/null
+++ b/users/wpcarro/scratch/facebook/find-duplicate-optimize-for-space.py
@@ -0,0 +1,22 @@
+import random
+
+def find_duplicate(xs):
+    print(xs)
+    # entry point in our cycle is the duplicate
+    i = xs[0]
+    j = xs[xs[0]]
+    while i != j:
+        print(i, xs[i], j, xs[j])
+        i = xs[i]
+        j = xs[xs[j]]
+    # detect cycle
+    j = 0
+    while i != j:
+        i = xs[i]
+        j = xs[j]
+    return xs[i]
+
+n = random.randint(5, 10)
+xs = [random.randint(0, n - 1) for _ in range(n)]
+result = find_duplicate(xs)
+print(xs, result)