Makhabat - Cedar

linked_list/linked_list.py

@@ -1,96 +1,165 @@
 
 # Defines a node in the singly linked list
-class Node:
+from platform import node
+
 
-    def __init__(self, value, next_node = None):
+class Node:
+    def __init__(self, value, next_node=None):
         self.value = value
         self.next = next_node
 
 # Defines the singly linked list
+
+
 class LinkedList:
     def __init__(self):
-      self.head = None # keep the head private. Not accessible outside this class
+        self.head = None  # keep the head private. Not accessible outside this class
 
     # returns the value in the first node
     # returns None if the list is empty
-    # Time Complexity: ?
-    # Space Complexity: ?
+       # Time Complexity: O(1)
+    # Space Complexity: O(1)
     def get_first(self):
-        pass
-
+        if self.head == None:
+            return None
+        return self.head.value
 
     # method to add a new node with the specific data value in the linked list
     # insert the new node at the beginning of the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
+
     def add_first(self, value):
-        pass
+        self.head = Node(value, self.head)
 
     # method to find if the linked list contains a node with specified value
     # returns true if found, false otherwise
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def search(self, value):
-        pass
+        if self.head == None:
+            return False
+        current = self.head
+        while current != None:
+            if current.value == value:
+                return True
+            current = current.next
+        return False
 
     # method that returns the length of the singly linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def length(self):
-        pass
+        lenght = 0
+        current = self.head
+        while current != None:
+            lenght += 1
+            current = current.next
+        return lenght
 
     # method that returns the value at a given index in the linked list
     # index count starts at 0
     # returns None if there are fewer nodes in the linked list than the index value
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
+
     def get_at_index(self, index):
-        pass
+        i = 0
+        current = self.head
+        while current != None:
+            if i == index:
+                return current.value
+            current = current.next
+            i += 1
+        return None
 
     # method that returns the value of the last node in the linked list
     # returns None if the linked list is empty
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def get_last(self):
-        pass
+        if self.head == None:
+            return None
+        current = self.head
+        while current != None:
+            if current.next == None:
+                return current.value
+            current = current.next
 
     # method that inserts a given value as a new last node in the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
+
     def add_last(self, value):
-        pass
+        if self.head == None:
+            self.add_first(value)
+        else:
+            current = self.head
+            while current.next != None:
+                current = current.next
+            current.next = Node(value)
 
     # method to return the max value in the linked list
     # returns the data value and not the node
+
     def find_max(self):
-        pass
+        if self.head == None:
+            return None
+        current = self.head
+        max = current.value
+        while current != None:
+            if current.value > max:
+                max = current.value
+            current = current.next
+        return max
 
     # method to delete the first node found with specified value
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def delete(self, value):
-        pass
+        if self.head == None:
+            return None
+        if self.head.value == value:
+            self.head = self.head.next
+        else:
+            current = self.head
+            while current.next.value != value:
+                current = current.next
+            current.next = current.next.next
 
     # method to print all the values in the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(n)
+
     def visit(self):
         helper_list = []
         current = self.head
 
         while current:
             helper_list.append(str(current.value))
             current = current.next
-        
+
         print(", ".join(helper_list))
 
     # method to reverse the singly linked list
     # note: the nodes should be moved and not just the values in the nodes
     # Time Complexity: ?
     # Space Complexity: ?
     def reverse(self):
-        pass
-
+        if self.head == None:
+            return None
+        if self.head.next == None:
+            return self.head
+        next_node = self.head.next
+        self.head.next = None
+        current = self.head
+        while (next_node != None):
+            temp_var = next_node.next
+            next_node.next = current
+            current = next_node
+            next_node = temp_var
+        self.head = current
+
     ## Advanced/ Exercises
     # returns the value at the middle element in the singly linked list
     # Time Complexity: ?
@@ -125,4 +194,4 @@ def create_cycle(self):
         while current.next != None:
             current = current.next
 
-        current.next = self.head # make the last node link to first node
+        current.next = self.head  # make the last node link to first node