python: init shuffle algorithm

python/shuffle/README.md

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+*How to shuffle the characters in a string in JavaScript ?*
+
+e.g. Given "ABCDEFG", return something like "GEFBDCA".
+
+```js
+print(shuffle("the quick brown fox jumps over the lazy dog"));
+//-> "veolrm  hth  ke opynug tusbxq ocrad ofeizwj"
+
+print(shuffle("the quick brown fox jumps over the lazy dog"));
+//-> "o dt hutpe u iqrxj  yaenbwoolhsvmkcger ozf "
+```
+
+- Best performance case: O(n)
+- Worst performance case: O(n log n)

python/shuffle/solution.py

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+#!/usr/bin/python3
+
+import math
+import random
+import unittest
+
+def shuffle(n):
+  arr = list(n)
+
+  for i in range(0, len(arr)):
+    j = math.floor(random.random() * (1 + i))
+    tmp = arr[i]
+    arr[i] = arr[j]
+    arr[j] = tmp
+
+  return ''.join(arr)
+
+class TestStringMethods(unittest.TestCase):
+
+    def test_shuffle(self):
+        string = 'my passphrase to shuffle'
+        self.assertNotEqual(shuffle(string), string)
+
+    def test_shuffle2(self):
+        string = 'a'
+        self.assertEqual(shuffle(string), string)
+
+    def test_shuffle3(self):
+        string = 'a b'
+        self.assertIn(shuffle(string), ['a b', 'b a', ' ba', 'ba ', 'ab ', ' ab'])
+
+if __name__ == '__main__':
+    unittest.main()