linked list

python/app/linked_list.py

@@ -0,0 +1,33 @@
+class Node:
+
+    def __init__(self, val):
+        self.val = val
+        self.next = None
+
+    def traverse(self):
+        n = self
+        while n is not None:
+            print n.val
+            n = n.next
+
+    def delete(self, node):
+        n = self
+        while n.next is not node:
+            n = n.next
+
+        n.next = node.next
+
+    def kth_from_last(self, count):
+        n = self
+        ref = self
+
+        i = 1
+        while i < count:
+            ref = ref.next
+            i += 1
+
+        while ref.next is not None:
+            n = n.next
+            ref = ref.next
+
+        return n

python/tests/test_linked_list.py

@@ -0,0 +1,50 @@
+from app.linked_list import Node
+
+
+def test_add_nodes(capfd):
+    node1 = Node(1)
+    node2 = Node(2)
+    node3 = Node(3)
+
+    node1.next = node2
+    node2.next = node3
+
+    node1.traverse()
+    out, err = capfd.readouterr()
+    assert out == '1\n2\n3\n'
+
+
+def test_delete_node(capfd):
+    node1 = Node(1)
+    node2 = Node(2)
+    node3 = Node(3)
+
+    node1.next = node2
+    node2.next = node3
+
+    node1.delete(node2)
+    node1.traverse()
+    out, err = capfd.readouterr()
+    assert out == '1\n3\n'
+
+    node1.delete(node3)
+    node1.traverse()
+    out, err = capfd.readouterr()
+    assert out == '1\n'
+
+
+def test_kth_from_last():
+    node1 = Node(1)
+    node2 = Node(2)
+    node3 = Node(3)
+    node4 = Node(4)
+    node5 = Node(5)
+
+    node1.next = node2
+    node2.next = node3
+    node3.next = node4
+    node4.next = node5
+
+    assert node1.kth_from_last(2) == node4
+    assert node1.kth_from_last(1) == node5
+    assert node1.kth_from_last(5) == node1