From 1e7975a9a78f3e780d82f351b812968813d536ff Mon Sep 17 00:00:00 2001
From: Thierry Joux <tjoux@hotmail.com>
Date: Fri, 20 Sep 2019 08:48:20 -0700
Subject: [PATCH 1/3] Completed ring_buffer class

---
 ring_buffer/ring_buffer.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/ring_buffer/ring_buffer.py b/ring_buffer/ring_buffer.py
index 35fd33cac..5a05c51a4 100644
--- a/ring_buffer/ring_buffer.py
+++ b/ring_buffer/ring_buffer.py
@@ -4,8 +4,11 @@ def __init__(self, capacity):
     self.current = 0
     self.storage = [None]*capacity
 
+  # when full always append by replacing the oldest information - not full replace the first preset None seen
   def append(self, item):
-    pass
+    self.storage[self.current % self.capacity] = item
+    self.current = (self.current + 1) % self.capacity
 
+  # return everything from buffer, in order, ignoring None values
   def get(self):
-    pass
\ No newline at end of file
+    return [item for item in self.storage if item is not None]
\ No newline at end of file

From d934c26818ce6195fd3204c0b25581f3a2619a1e Mon Sep 17 00:00:00 2001
From: Thierry Joux <tjoux@hotmail.com>
Date: Fri, 20 Sep 2019 10:17:42 -0700
Subject: [PATCH 2/3] Completed names.py + STRETCH

---
 names/binary_search_tree.py | 44 +++++++++++++++++++++++++++++++++++++
 names/names.py              | 38 +++++++++++++++++++++++++++-----
 2 files changed, 77 insertions(+), 5 deletions(-)
 create mode 100644 names/binary_search_tree.py

diff --git a/names/binary_search_tree.py b/names/binary_search_tree.py
new file mode 100644
index 000000000..0490a9913
--- /dev/null
+++ b/names/binary_search_tree.py
@@ -0,0 +1,44 @@
+class BinarySearchTree:
+  def __init__(self, value):
+    self.value = value
+    self.left = None
+    self.right = None
+
+
+  def insert(self, value):
+
+    if value == self.value:
+      return
+
+    if value < self.value:
+      if not self.left:
+        self.left = BinarySearchTree(value)
+      else:
+        self.left.insert(value)
+    
+    elif value > self.value:
+      if not self.right:
+        self.right = BinarySearchTree(value)
+      else:
+        self.right.insert(value)
+    
+
+
+
+  def contains(self, target):
+
+    if self.value == target:
+      return True
+
+    if target < self.value:
+
+      if self.left:
+        return self.left.contains(target)
+      else:
+        return False
+
+    else:
+      if self.right:
+        return self.right.contains(target)
+      else:
+        return False
\ No newline at end of file
diff --git a/names/names.py b/names/names.py
index 586e8393e..73c8b31ed 100644
--- a/names/names.py
+++ b/names/names.py
@@ -1,4 +1,5 @@
 import time
+from binary_search_tree import BinarySearchTree
 
 start_time = time.time()
 
@@ -10,11 +11,38 @@
 names_2 = f.read().split("\n")  # List containing 10000 names
 f.close()
 
-duplicates = []
-for name_1 in names_1:
-    for name_2 in names_2:
-        if name_1 == name_2:
-            duplicates.append(name_1)
+###########################################################################
+# Binary Tree Search solution (insertion complexity: O(h(eight of tree)), 
+# comparison: n * O(h(eight of tree))
+###########################################################################
+
+# Setup binary tree and insert all names of names_1
+bst = BinarySearchTree(names_1[0])
+
+for i in range(1,len(names_1)):
+    bst.insert(names_1[i])
+
+# look up for duplicates
+duplicates=[]
+for name in names_2:
+    if bst.contains(name):
+        duplicates.append(name)
+
+#####################################
+# Original solution (runtime: 5.5 s.)
+# complexity: O(n**2)
+######################################
+# duplicates = []
+# for name_1 in names_1:
+#     for name_2 in names_2:
+#         if name_1 == name_2:
+#             duplicates.append(name_1)
+
+######## ############################## STRETCH ###################################
+# STRETCH - only Python lists - No extra storage for binary tree  (runtime: 1.11 s.)
+####################################################################################
+# 
+# duplicates = [name for name in names_1 if name in names_2]
 
 end_time = time.time()
 print (f"{len(duplicates)} duplicates:\n\n{', '.join(duplicates)}\n\n")

From b8cfbad5476da653fcd86f6998b7b086dffc8238 Mon Sep 17 00:00:00 2001
From: Thierry Joux <tjoux@hotmail.com>
Date: Fri, 20 Sep 2019 10:47:55 -0700
Subject: [PATCH 3/3] Completed reverse_list function

---
 reverse/reverse.py | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/reverse/reverse.py b/reverse/reverse.py
index 95ed9d1d4..c23f79b88 100644
--- a/reverse/reverse.py
+++ b/reverse/reverse.py
@@ -43,5 +43,20 @@ def contains(self, value):
     return False
 
   def reverse_list(self):
-    # TO BE COMPLETED
-    pass
\ No newline at end of file
+
+    if self.head is None or self.head.next_node is None:
+      return
+
+    #reverting direction for all linked list pointers
+    previous = None
+    current = self.head
+    after = current.next_node
+
+    while after is not None:
+      current.next_node = previous
+      previous = current
+      current = after
+      after = current.next_node
+    
+    current.next_node = previous
+    self.head = current
\ No newline at end of file