Ports - Sopheary

lib/tree.rb

@@ -16,47 +16,149 @@ def initialize
     @root = nil
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n)
+  # Space Complexity: O(1)
   def add(key, value)
-    raise NotImplementedError
+    new_node = TreeNode.new(key, value)
+    if @root.nil?
+      @root = new_node
+      return
+    end
+
+    add_helper(@root, new_node)
+  end
+
+  def add_helper(tree_node, new_node)
+    if tree_node.nil?
+      tree_node = new_node
+    end
+
+    return tree_node if tree_node.key == new_node.key
+
+    if new_node.key < tree_node.key
+      if tree_node.left.nil?
+        tree_node.left = new_node
+      else
+        add_helper(tree_node.left, new_node)
+      end
+    end
+
+    if new_node.key > tree_node.key
+      if tree_node.right.nil?
+        tree_node.right = new_node
+      else
+        add_helper(tree_node.right, new_node)
+      end
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(log n)
+  # Space Complexity: O(1)
   def find(key)
-    raise NotImplementedError
+    return nil if @root.nil?
+    return find_helper(@root, key)
+  end
+
+  def find_helper(tree_node, key)
+    return nil if tree_node.nil?
+    return tree_node.value if tree_node.key == key
+    return find_helper(tree_node.left, key) if key < tree_node.key
+    return find_helper(tree_node.right, key)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes
+  # Space Complexity: O(n) where n is the number of nodes
   def inorder
-    raise NotImplementedError
+    return [] if @root.nil?
+    return inorder_helper(@root)
+  end
+
+  def inorder_helper(tree_node, array = [])
+    return array if tree_node.nil?
+    if tree_node
+      inorder_helper(tree_node.left, array)
+      array << {key: tree_node.key, value: tree_node.value}
+      inorder_helper(tree_node.right, array)
+    end
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes
+  # Space Complexity: O(n) where n is the number of nodes
   def preorder
-    raise NotImplementedError
+    return [] if @root.nil?
+    return preorder_helper(@root)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def preorder_helper(root)
+    return if root.nil?
+    array = []
+    array << root
+    nodeStack = []
+
+    while array.length > 0
+      node = array.pop
+      nodeStack << {key: node.key, value: node.value}
+      if node.right != nil 
+        array << node.right
+      end
+
+      if node.left != nil
+        array << node.left
+      end
+    end
+    return nodeStack
+  end
+
+  # Time Complexity: O(n) where n is the number of nodes
+  # Space Complexity: O(n) where n is the length of the tree
   def postorder
-    raise NotImplementedError
+    return [] if @root.nil?
+    return postorder_helper(@root)
   end
 
-  # Time Complexity: 
-  # Space Complexity: 
+  def postorder_helper(tree_node, array = [])
+    return array if tree_node.nil?
+
+    if tree_node
+      postorder_helper(tree_node.left, array)
+      postorder_helper(tree_node.right, array)
+      array << {key: tree_node.key, value: tree_node.value}
+    end
+  end
+
+  # Time Complexity: O(n) where n is the number of nodes
+  # Space Complexity: O(1)
   def height
-    raise NotImplementedError
+    return 0 if @root.nil?
+    return height_helper(@root)
+  end
+
+  def height_helper(tree_node)
+    return 0 if tree_node.nil?
+    left_height = height_helper(tree_node.left)
+    right_height = height_helper(tree_node.right)
+    if left_height > right_height
+      return left_height + 1
+    else
+      return right_height + 1
+    end
   end
 
   # Optional Method
-  # Time Complexity: 
-  # Space Complexity: 
+  # Time Complexity: O(n) where n is the number of nodes
+  # Space Complexity: O(n) where is is the length of the tree
   def bfs
-    raise NotImplementedError
+    return [] if @root.nil?
+    queue = []
+    output = []
+    queue << @root
+    while (!queue.empty?)
+      current = queue.shift
+      if(current.left) then queue.push(current.left) end
+      if(current.right) then queue.push(current.right) end
+        output.push({key: current.key, value: current.value})
+    end
+    return output
   end
 
   # Useful for printing