C-14 Fire Alice D

lib/linked_list.rb

@@ -18,71 +18,163 @@ def initialize
 
     # 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(value)
-      raise NotImplementedError
+
+      new_node = Node.new(value, nil)
+      new_node.next = @head
+      @head = new_node
+      return @head.data
     end
 
     # 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(value)
-      raise NotImplementedError
+      current = @head
+      while current != nil
+        if current.data == value
+          return true
+        else
+          current = current.next
+        end
+      end
+      return false
     end
 
     # method to return the max value in the linked list
     # returns the data value and not the node
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def find_max
-      raise NotImplementedError
+      return nil if @head.nil?
+      current = @head
+      max_value = @head.data
+      while current != nil
+        if current.data > max_value
+          max_value = current.data
+        end
+        current = current.next
+      end
+      return max_value
     end
 
     # method to return the min value in the linked list
     # returns the data value and not the node
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def find_min
-      raise NotImplementedError
+      return nil if @head.nil?
+      current = @head
+      min_value = current.data
+      while current != nil
+        if current.data < min_value
+          min_value = current.data
+        end
+        current = current.next
+      end
+      return min_value
+
     end
 
 
     # method that returns the length of the singly linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def length
-      raise NotImplementedError
+      return 0 if @head.nil?
+      current = @head
+      length = 0
+      while current != nil
+        length += 1
+        current = current.next
+      end
+      return length
     end
 
     # method that returns the value at a given index in the linked list
     # index count starts at 0
     # returns nil 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(index)
-      raise NotImplementedError
+      # traverse the list,
+      #  index, number of times or
+      #  until the end is reach
+      #  Then return the current node's value
+      i = 0
+      current = @head
+      while current != nil
+        if i == index
+          return current.data
+        else
+          i += 1
+          current = current.next
+        end
+      end
+
+      return nil
+
     end
 
     # method to print all the values in the linked list
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def visit
-      raise NotImplementedError
+      current = @head
+      while current !=nil
+        puts current.data
+        current = current.next
+        end
     end
 
     # method to delete the first node found with specified value
-    # Time Complexity: ?
-    # Space Complexity: ?
+    # Time Complexity: O(n)
+    # Space Complexity: O(1)
     def delete(value)
-      raise NotImplementedError
+
+      if @head.nil?
+        return
+      end
+
+      if @head.data == value
+        @head = @head.next
+        return
+      end
+
+      current = @head
+      previous = nil
+
+      while current != nil
+        if current.data == value
+          previous.next = current.next
+        end
+        previous = current
+        current = current.next
+      end
     end
 
     # 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(1)
     def reverse
-      raise NotImplementedError
+      if @head.nil? || @head.next.nil?
+        return @head
+      end
+
+      current = @head
+      previous = nil
+
+      while current != nil
+        temp = current.next
+        current.next = previous
+        previous = current
+        current = temp
+      end
+      @head = previous
     end
 
 
@@ -118,7 +210,12 @@ def has_cycle
     # Time Complexity: ?
     # Space Complexity: ?
     def get_first
-      raise NotImplementedError
+      # return the value of the 1st node in the list
+      if @head.nil?
+        return nil
+      else
+        return @head.data
+      end
     end
 
     # method that inserts a given value as a new last node in the linked list
@@ -133,6 +230,9 @@ def add_last(value)
     # Time Complexity: ?
     # Space Complexity: ?
     def get_last
+      # return nil if the list is empty
+      # otherwise traverse the list to the end
+      # Then return the last node's value
       raise NotImplementedError
     end