Space - Chelsea

lib/tree.rb

@@ -14,42 +14,172 @@ class Tree
   attr_reader :root
   def initialize
     @root = nil
+    @inOrderArray = []
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: log n because it is binary to find where to add the node
+  # Space Complexity: worst case O(n) because we hit every node better average case like in a balanced tree it would be O(log n)
   def add(key, value)
-    raise NotImplementedError
+    if @root == nil
+      @root = TreeNode.new(key, value)
+      return
+    end
+
+    current = @root
+    add_helper(current, key, value)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def add_helper(current, key, value)
+    if current.key >= key
+      if current.left
+        current = current.left
+        add_helper(current, key, value)
+      else
+        newNode = TreeNode.new(key, value)
+        current.left = newNode
+      end
+    elsif current.key < key
+
+      if current.right
+        current = current.right
+        add_helper(current, key, value)
+      else
+        newNode = TreeNode.new(key, value)
+        current.right = newNode
+      end
+    end 
+  end
+
+  # Time Complexity: log n due to the binary search
+  # Space Complexity: worst case O(n) because we hit every node better average case like in a balanced tree it would be O(log n)
   def find(key)
-    raise NotImplementedError
+    if !@root
+      return nil
+    end
+
+    current = @root
+    return find_helper(current, key)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def find_helper(current, searchKey)
+    if current.key == searchKey
+      return current.value
+    end
+
+    if current.key > searchKey
+      current = current.left
+      return find_helper(current, searchKey)
+    elsif current.key < searchKey
+      current = current.right
+      return find_helper(current, searchKey)
+    end
+  end
+
+  # Time Complexity: O(n) because it has to go through every node.
+  # Space Complexity: worst case O(n) because we hit every node better average case like in a balanced tree it would be O(log n)
   def inorder
-    raise NotImplementedError
+    if @root == nil
+      return []
+    end
+
+    current = @root
+    getInOrder(current)
+    return @inOrderArray
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def getInOrder(node)
+    if node.left != nil
+      getInOrder(node.left)
+    end
+
+    @inOrderArray.push({:key=>node.key, :value=>node.value})
+
+    if node.right != nil
+      getInOrder(node.right)
+    end
+  end
+
+  # Time Complexity: O(n) because it has to go through every node.
+  # Space Complexity: worst case O(n) because we hit every node better average case like in a balanced tree it would be O(log n)
   def preorder
-    raise NotImplementedError
+    if @root == nil
+      return []
+    end
+
+    current = @root
+    getPreOrder(current)
+    return @inOrderArray
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def getPreOrder(node)
+    @inOrderArray.push({:key=>node.key, :value=>node.value})
+
+    if node.left != nil
+      getPreOrder(node.left)
+    end
+
+    if node.right != nil
+      getPreOrder(node.right)
+    end
+  end
+
+  # Time Complexity: O(n) because it has to go through every node.
+  # Space Complexity: worst case O(n) because we hit every node, better average case like in a balanced tree it would be O(log n)
   def postorder
-    raise NotImplementedError
+    if @root == nil
+      return []
+    end
+
+    current = @root
+    getPostOrder(current)
+    return @inOrderArray
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def getPostOrder(node)
+
+    if node.left != nil
+      getPostOrder(node.left)
+    end
+
+    if node.right != nil
+      getPostOrder(node.right)
+    end
+
+    @inOrderArray.push({:key=>node.key, :value=>node.value})
+  end
+
+  # Time Complexity: O(n) because we hit eery node
+  # Space Complexity: worst case O(n) because we hit every node better average case like in a balanced tree it would be O(log n)
   def height
-    raise NotImplementedError
+    if @root == nil
+      return 0
+    end
+
+    current = @root
+    height = 1
+
+    height = getHeight(current, height)
+    return height
+  end
+
+  def getHeight(node, height)
+
+    left = height
+    right = height
+
+    if node.left != nil
+      left = getHeight(node.left, height +1)
+    end
+
+    if node.right != nil
+      right = getHeight(node.right, height + 1)
+    end
+
+    if left >= right
+      return left
+    else
+      return right
+    end
   end
 
   # Optional Method