hmmm

tree-practice.rb

@@ -8,14 +8,110 @@ def initialize(val)
    end
 end
 
+# 1.
+# start with base case node is nil
+# check left nodes all the way down
+# if a node is an operator, print it
+# check right nodes all the way down
+def print_operators(node)
+  operators = ["+", "-", "%", "*", "/"]
+  return if node == nil
+  print_operators(node.left)
+    if operators.include?(node.value)
+      print node.value
+    end
+  print_operators(node.right)
+end
+
+# 2.
+# start with base case node is nil
+# check left nodes all the way down
+# if a node is an operand, print it
+# check right nodes all the way down
+def print_non_operators(node)
+  operators = ["+", "-", "%", "*", "/"]
+  return if node == nil
+  print_non_operators(node.left)
+    unless operators.include?(node.value)
+      print node.value
+    end
+  print_non_operators(node.right)
+end
+
+# def count_non_operators(node, count = 0)
+#   operators = ["+", "-", "%", "*", "/"]
+#   if node == nil
+#     puts count
+#     return count
+#   end
+#   count_non_operators(node.left, count)
+#     if node.left == nil && node.right == nil
+#       count_non_operators(node, count += 1)
+#     end
+#   count_non_operators(node.right, count)
+#     if node.left == nil && node.right == nil
+#       count += 1
+#     end
+# end
+
+# root = TreeNode.new("-")
+# root.left = TreeNode.new("+")
+# root.right = TreeNode.new("10")
+# root.left.left = TreeNode.new("3")
+# root.left.right = TreeNode.new("2")
+# count_non_operators(root)
+
+# 3.
 def print_infix(node)
   return if node == nil
   print_infix(node.left)
   print node.value + " "
   print_infix(node.right)
 end
 
-root = TreeNode.new("+")
-root.left = TreeNode.new("3")
-root.right = TreeNode.new("2")
-print_infix(root)
+# check left
+# check right
+# print value
+def print_postfix(node)
+  return if node == nil
+  print_postfix(node.left)
+  print_postfix(node.right)
+  print node.value + " "
+end
+
+# print node
+# check left
+# check right
+def print_prefix(node)
+  return if node == nil
+  print node.value + " "
+  print_postfix(node.left)
+  print_postfix(node.right)
+end
+
+ # 1.    3 + 2
+ # 2.    3 + 2 - 10
+ # 3.    4 * 3 + 2
+ # 4.    4 * 3 + 2 - 10 % 5
+
+# root = TreeNode.new("+")
+# root.left = TreeNode.new("3")
+# root.right = TreeNode.new("2")
+# print_infix(root)
+
+# 3 + 2 - 10
+
+# root = TreeNode.new("-")
+# root.left = TreeNode.new("+")
+# root.right = TreeNode.new("10")
+# root.left.left = TreeNode.new("3")
+# root.left.right = TreeNode.new("2")
+# print_infix(root)
+# print_postfix(root)
+
+# root = TreeNode.new("+")
+# root.left = TreeNode.new("*")
+# root.right = TreeNode.new("2")
+# root.left.left = TreeNode.new("4")
+# root.left.right = TreeNode.new("3")
+# print_operators(root)