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, 45 insertions, 0 deletions

diff --git a/users/wpcarro/scratch/data_structures_and_algorithms/find-unique-int-among-duplicates.py b/users/wpcarro/scratch/data_structures_and_algorithms/find-unique-int-among-duplicates.py
new file mode 100644
index 0000000000..dfa5de42cc
--- /dev/null
+++ b/users/wpcarro/scratch/data_structures_and_algorithms/find-unique-int-among-duplicates.py
@@ -0,0 +1,45 @@
+import unittest
+
+
+################################################################################
+# Solution
+################################################################################
+def find_unique_delivery_id(xs):
+    a = 0
+    for x in xs:
+        a ^= x
+    return a
+
+
+################################################################################
+# Tests
+################################################################################
+class Test(unittest.TestCase):
+    def test_one_drone(self):
+        actual = find_unique_delivery_id([1])
+        expected = 1
+        self.assertEqual(actual, expected)
+
+    def test_unique_id_comes_first(self):
+        actual = find_unique_delivery_id([1, 2, 2])
+        expected = 1
+        self.assertEqual(actual, expected)
+
+    def test_unique_id_comes_last(self):
+        actual = find_unique_delivery_id([3, 3, 2, 2, 1])
+        expected = 1
+        self.assertEqual(actual, expected)
+
+    def test_unique_id_in_middle(self):
+        actual = find_unique_delivery_id([3, 2, 1, 2, 3])
+        expected = 1
+        self.assertEqual(actual, expected)
+
+    def test_many_drones(self):
+        actual = find_unique_delivery_id(
+            [2, 5, 4, 8, 6, 3, 1, 4, 2, 3, 6, 5, 1])
+        expected = 8
+        self.assertEqual(actual, expected)
+
+
+unittest.main(verbosity=2)