dibs: implement simple-linked-list

config.json

@@ -429,6 +429,12 @@
  "difficulty": 1,
  "topics": [
  ]
+ },
+ {
+ "slug": "simple-linked-list",
+ "difficulty": 1,
+ "topics": [
+ ]
  }
  ],
  "deprecated": [

exercises/simple-linked-list/example.py

@@ -0,0 +1,67 @@
+class Element(object):
+ def __init__(self, value):
+ self.value = value
+ self.next = None
+
+
+class LinkedList(object):
+ def __init__(self, head=None):
+ self.head = head
+ self.size = 0
+
+ def push(self, new_element):
+ new_e = Element(new_element)
+
+ if self.empty():
+ self.head = new_e
+ else:
+ new_e.next = self.head
+ self.head = new_e
+ self.size += 1
+
+ def pop(self):
+ if self.empty():
+ return None
+ else:
+ e = self.head
+ self.head = self.head.next
+ self.size -= 1
+ return e.value
+
+ def empty(self):
+ return self.size == 0
+
+ def get_peek(self):
+ if self.empty():
+ return None
+ else:
+ return self.head.value
+
+ def reverse(self):
+ new_list = LinkedList()
+ if self.size > 0:
+ current = self.head
+ while current.next:
+ new_list.push(current.value)
+ current = current.next
+ new_list.push(current.value)
+ return new_list
+
+ def to_array(self):
+ arr = []
+ if self.empty():
+ return []
+ current = self.head
+ while current.next:
+ arr.append(current.value)
+ current = current.next
+ arr.append(current.value)
+ return arr
+
+ def from_array(self, arr=[]):
+ if len(arr) == 0:
+ return self
+ else:
+ for i in arr:
+ self.push(i)
+ return self

exercises/simple-linked-list/simple-linked-list_test.py

@@ -0,0 +1,65 @@
+import unittest
+
+from simple_linked_list import LinkedList
+
+
+class LinkedListTests(unittest.TestCase):
+ def setUp(self):
+ self.slist = LinkedList()
+
+ def test_size(self):
+ self.slist.push(0)
+ self.assertEqual(1, self.slist.size)
+ # notice if size is increased
+ self.slist.push(1)
+ self.assertEqual(2, self.slist.size)
+ self.slist.push(2)
+ self.assertEqual(3, self.slist.size)
+
+ def test_pop(self):
+ # with cero element
+ self.assertIsNone(self.slist.pop())
+ # with multiple elements
+ self.slist.push(1)
+ self.slist.push(2)
+ self.slist.push(3)
+ self.assertEqual(3, self.slist.pop())
+ self.assertEqual(2, self.slist.pop())
+ self.assertEqual(1, self.slist.pop())
+ self.assertIsNone(self.slist.pop())
+
+ def test_reverse(self):
+ # empty reversed LinkedList
+ empty_reversed = self.slist.reverse()
+ self.assertEqual(0, empty_reversed.size)
+ self.assertIsNone(empty_reversed.head)
+ # push_elements
+ self.slist.push(1)
+ self.slist.push(2)
+ self.slist.push(3)
+ self.slist.push(4)
+ reversed_list = self.slist.reverse()
+ self.assertEqual(1, reversed_list.head.value)
+ self.assertEqual(1, reversed_list.get_peek())
+
+ def test_to_array(self):
+ # in : empty list out : empty array
+ self.assertListEqual([], self.slist.to_array())
+ # push_elements
+ self.slist.push(1)
+ self.slist.push(2)
+ self.slist.push(3)
+ self.slist.push(4)
+ self.assertListEqual([4, 3, 2, 1], self.slist.to_array())
+
+ def test_from_array(self):
+ # in : empty array out : empty list
+ self.assertIsNone(self.slist.from_array([]).head)
+ # push_elements
+ new_arr = [1, 2, 3, 4]
+ self.assertEqual(4, self.slist.from_array(new_arr).head.value)
+ self.assertEqual(4, self.slist.from_array(new_arr).get_peek())
+
+
+if __name__ == '__main__':
+ unittest.main()