Finished Data Structures Python

names/names.py

@@ -13,10 +13,17 @@
 duplicates = []  # Return the list of duplicates in this data structure
 
 # Replace the nested for loops below with your improvements
-for name_1 in names_1:
-    for name_2 in names_2:
-        if name_1 == name_2:
-            duplicates.append(name_1)
+# for name_1 in names_1:
+#     for name_2 in names_2:
+#         if name_1 == name_2:
+#             duplicates.append(name_1)
+#             # runtime: 6.383997678756714 seconds
+
+with open('names_1.txt') as f1, open('names_2.txt') as f2:
+    for line in set(line.strip() for line in f1) & set(line.strip() for line in f2):
+        if line:
+            duplicates.append(line)
+            # runtime: 0.008002042770385742 seconds
 
 end_time = time.time()
 print (f"{len(duplicates)} duplicates:\n\n{', '.join(duplicates)}\n\n")

reverse/reverse.py

@@ -38,5 +38,16 @@ def contains(self, value):
 
         return False
 
-    def reverse_list(self, node, prev):
-        pass
+    def reverse_list(self, node, prev=None):
+        while node is not None:
+            # we hold a reference for the node's next node
+            next = node.next_node
+            # in the beginning, set to None, like how the tail is set to None
+            # Then afterwards the next_node is set to the prev node of the current nod
+            node.next_node = prev
+            # prev set to node for later use in the while loop
+            prev = node
+            # We then go on to the node's next node to change its pointer
+            node = next
+        # we set a new head of the final node that we changed
+        self.head = prev

ring_buffer/ring_buffer.py

@@ -1,9 +1,40 @@
+# https://www.youtube.com/watch?v=ia__kyuwGag&t=627s
+
 class RingBuffer:
     def __init__(self, capacity):
-        pass
+        self.capacity = capacity
+        self.index = 0
+        self.storage = []
 
     def append(self, item):
-        pass
+        if len(self.storage) is self.capacity:
+            self.storage[self.index] = item
+        else:
+            self.storage.append(item)
+        self.index = (self.index + 1) % self.capacity
 
     def get(self):
-        pass
+        return self.storage
+
+
+if __name__ == '__main__':
+    buffer = RingBuffer(3)
+
+    print(buffer.get())  # should return []
+
+    buffer.append('a')
+    buffer.append('b')
+    buffer.append('c')
+    print(len(buffer.get()))
+    print(buffer.get())  # should return ['a', 'b', 'c']
+
+    # 'd' overwrites the oldest value in the ring buffer, which is 'a'
+    buffer.append('d')
+
+    print(buffer.get())  # should return ['d', 'b', 'c']
+
+    buffer.append('e')
+    print(buffer.get())
+    buffer.append('f')
+
+    print(buffer.get())  # should return ['d', 'e', 'f']