Shaina Beth C16 Spruce

linked_list/linked_list.py

@@ -13,67 +13,126 @@ def __init__(self):
 
     # 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(1)
+    # Space Complexity: O(1)
     def add_first(self, value):
-        pass
+        new_head = Node(value, self.head)
+        self.head = new_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
+        cur = self.head
+        while cur != None:
+            if cur.value == value:
+                return True
+            cur = cur.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
+        cur = self.head
+        i = 0
+        while cur != None:
+            cur = cur.next
+            i += 1
+        return i
 
     # 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
+        cur = self.head
+        for i in range(index):
+            if cur == None:
+                return None
+            cur = cur.next
+        return cur.value
+
 
     # 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
+        cur = self.head
+        prev = None
+        while cur != None:
+            prev = cur
+            cur = cur.next
+        return prev.value
 
     # 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.head = Node(value, None)
+            return
+        cur = self.head
+        prev = None
+        while cur != None:
+            prev = cur
+            cur = cur.next
+        prev.next = Node(value, None)
+
 
     # 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
+        cur = self.head
+        cur_max = cur.value
+        cur = cur.next
+        while cur != None:
+            if cur.value > cur_max:
+                cur_max = cur.value
+            cur = cur.next
+        return cur_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
+
+        prev = self.head
+        cur = self.head.next
+        while cur != None and cur.value != value:
+            prev = cur
+            cur = cur.next
+
+        if cur != None:
+            prev.next = cur.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
@@ -86,10 +145,15 @@ def visit(self):
 
     # 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: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(n)
     def reverse(self):
-        pass
+        cur = self.head
+        last_made = None
+        while cur != None:
+            last_made = Node(cur.value, last_made)
+            cur = cur.next
+        self.head = last_made
 
     ## Advanced/ Exercises
     # returns the value at the middle element in the singly linked list