From 81d0e4d81ec55a0c9f5d5f9f7dcefe27e4f9db53 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9ssica=20Paz?= <jessicamorim.42@gmail.com>
Date: Tue, 30 Oct 2018 04:43:04 -0300
Subject: [PATCH] Add hailstone algorithm (#434)

* Add hailstone algorithm in maths

* Add hailstone in README file

* Change type terms to int

* Add hailstone test
---
 README.md                     |  1 +
 algorithms/maths/hailstone.py | 13 +++++++++++++
 tests/test_maths.py           | 15 ++++++++++++++-
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 algorithms/maths/hailstone.py

diff --git a/README.md b/README.md
index aecd53b6d..4443884e4 100644
--- a/README.md
+++ b/README.md
@@ -203,6 +203,7 @@ If you want to uninstall algorithms, it is as simple as:
     - [rsa](algorithms/maths/rsa.py)
     - [sqrt_precision_factor](algorithms/maths/sqrt_precision_factor.py)
     - [summing_digits](algorithms/maths/summing_digits.py)
+    - [hailstone](algorithms/maths/hailstone.py)
 - [matrix](algorithms/matrix)
     - [sudoku_validator](algorithms/matrix/sudoku_validator.py)
     - [bomb_enemy](algorithms/matrix/bomb_enemy.py)
diff --git a/algorithms/maths/hailstone.py b/algorithms/maths/hailstone.py
new file mode 100644
index 000000000..22321232b
--- /dev/null
+++ b/algorithms/maths/hailstone.py
@@ -0,0 +1,13 @@
+def hailstone(n):
+  """Return the 'hailstone sequence' from n to 1
+     n: The starting point of the hailstone sequence
+  """
+
+  sequence = [n]
+  while n > 1:
+    if n%2 != 0:
+      n = 3*n + 1
+    else: 
+      n = int(n/2)
+    sequence.append(n)
+  return sequence
\ No newline at end of file
diff --git a/tests/test_maths.py b/tests/test_maths.py
index 0777f9ab3..dd1d0e137 100644
--- a/tests/test_maths.py
+++ b/tests/test_maths.py
@@ -14,7 +14,8 @@
     pythagoras,
     is_prime,
     encrypt, decrypt,
-    combination, combination_memo
+    combination, combination_memo,
+    hailstone,
 )
 
 import unittest
@@ -288,5 +289,17 @@ def test_factorial_recur(self):
         self.assertRaises(ValueError, factorial_recur, 42, -1)
 
 
+class TestHailstone(unittest.TestCase):
+    """[summary]
+    Test for the file hailstone.py
+
+    Arguments:
+        unittest {[type]} -- [description]
+    """
+    def test_hailstone(self):
+        self.assertEqual([8, 4, 2, 1], hailstone.hailstone(8))
+        self.assertEqual([10, 5, 16, 8, 4, 2, 1], hailstone.hailstone(10))
+
+
 if __name__ == "__main__":
     unittest.main()