Water - Sophia

lib/tree.rb

@@ -1,56 +1,144 @@
 class TreeNode
   attr_reader :key, :value
   attr_accessor :left, :right
-
-   def initialize(key, val)
+  
+  def initialize(key, value)
     @key = key
-    @value = val
+    @value = value
     @left = nil
     @right = nil
-   end
+  end
 end
 
 class Tree
   attr_reader :root
   def initialize
     @root = nil
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: Olog(n)
+  # Space Complexity: O(1)
   def add(key, value)
-    raise NotImplementedError
+    new_node = TreeNode.new(key, value)
+    if @root.nil?
+      @root = new_node
+    else
+      add_helper(@root, new_node)
+    end
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+
+  def add_helper(current, new_node)
+    return new_node if current.nil?
+    if new_node.key <= current.key
+      current.left = add_helper(current.left, new_node)
+    else
+      current.right = add_helper(current.right, new_node)
+    end
+    return current
+  end
+
+  # Time Complexity: Olog(n)
+  # Space Complexity: O(1)
   def find(key)
-    raise NotImplementedError
+    return nil if @root.nil?
+    return @root.value if @root.key == key
+
+    current = @root
+    while current != nil
+      if key == current.key
+        return current.value
+      elsif key < current.key
+        current = current.left
+      elsif key > current.key
+        current = current.right
+      end
+    end
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: O(n) 
+  # Space Complexity: O(n)
   def inorder
-    raise NotImplementedError
+    return [] if @root.nil?
+    list = []
+    stack = []
+    current = @root
+
+
+    while !current.nil? || !stack.empty?
+
+      while !current.nil?
+        stack << current
+        current = current.left
+      end
+
+      current = stack.pop
+      list << {key: current.key, value: current.value}
+      current = current.right
+    end
+
+    return list
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
-  def preorder
-    raise NotImplementedError
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n)
+  def preorder 
+    return [] if @root.nil?
+    list = []
+    stack = []
+    current = @root
+
+    stack.push(current)
+    while !stack.empty?
+      current = stack.pop
+      list << {key: current.key, value: current.value}
+      stack << current.right if current.right
+      stack << current.left if current.left
+    end
+
+    return list
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
-  def postorder
-    raise NotImplementedError
+
+  # Time Complexity: O(n)
+  # Space Complexity: O(n) 
+  def postorder 
+    return [] if @root.nil?
+
+    list = []
+    s1 = []
+    s2 = []
+    current = @root
+
+    s1 << current
+    while !s1.empty?
+      current = s1.pop
+      s2 << current
+      s1 << current.left if current.left
+      s1 << current.right if current.right
+    end
+
+    while !s2.empty?
+      current = s2.pop
+      list << {key: current.key, value: current.value}
+    end
+
+    return list
   end
-
-  # Time Complexity: 
-  # Space Complexity: 
+  
+  # Time Complexity: Olog(n)
+  # Space Complexity: O(1)
   def height
-    raise NotImplementedError
+    return 0 if @root.nil?
+    return height_helper(@root)
   end
+
+  def height_helper(current)
+    if current.nil?
+      return 0
+    else
+      return 1 + [height_helper(current.left), height_helper(current.right)].max
+    end
+  end
+
 
   # Optional Method
   # Time Complexity: 
@@ -63,4 +151,4 @@ def bfs
   def to_s
     return "#{self.inorder}"
   end
-end
+end