Here's this!

README.md

@@ -1,7 +1,7 @@
 # Tree Practice
 
 ## Creating a binary tree on paper
-On paper, create a binary search tree to represent the expressions below.
+On paper, create a binary expression tree to represent the expressions below.
 1. `3 + 2`
 2. `3 + 2 - 10`
 3. `4 * 3 + 2`

tree-practice.rb

@@ -15,7 +15,96 @@ def print_infix(node)
   print_infix(node.right)
 end
 
+def print_prefix(node)
+  # base case
+  return if node == nil
+  print node.value + " "
+  print_prefix(node.left)
+  print_prefix(node.right)
+end
+
+def print_postfix(node)
+  return if node == nil
+  print_postfix(node.left)
+  print_postfix(node.right)
+  print node.value + " "
+end
+
+def operators(node)
+  return if node == nil
+  operators(node.left)
+  if node.value == "+" || node.value == "-" || node.value == "*" || node.value == "/" || node.value == "%"
+    print node.value + " "
+  end
+  operators(node.right)
+end
+
+def non_operators(node)
+  return if node == nil
+  non_operators(node.left)
+  unless node.value == "+" || node.value == "-" || node.value == "*" || node.value == "/" || node.value == "%"
+    print node.value + " "
+  end
+  non_operators(node.right)
+end
+
+def find_operator(node, operator)
+  if node == nil
+    return false
+  elsif node.value == operator
+    return true
+  end
+  find_operator(node.left, operator)
+  find_operator(node.right, operator)
+end
+
+## see other test cases on paper
+
+### trees we made in class ###
 root = TreeNode.new("+")
 root.left = TreeNode.new("3")
 root.right = TreeNode.new("2")
-print_infix(root)
+# print_infix(root)
+
+root2 = TreeNode.new("-")
+root2.left = TreeNode.new("+")
+root2.right = TreeNode.new("10")
+root2.left.left = TreeNode.new("3")
+root2.left.right = TreeNode.new("2")
+# print_infix(root2)
+
+puts ""
+
+root3 = TreeNode.new("+")
+root3.left = TreeNode.new("*")
+root3.right = TreeNode.new("2")
+root3.left.left = TreeNode.new("4")
+root3.left.right = TreeNode.new("3")
+# print_infix(root3)
+
+# puts ""
+
+root4 = TreeNode.new("-")
+root4.left = TreeNode.new("+")
+root4.right = TreeNode.new("%")
+root4.left.left = TreeNode.new("*")
+root4.left.right = TreeNode.new("2")
+root4.left.left.left = TreeNode.new("4")
+root4.left.left.right = TreeNode.new("3")
+root4.right.left = TreeNode.new("10")
+root4.right.right = TreeNode.new("5")
+# print_infix(root4)
+
+# puts ""
+
+### testing out methods
+#
+# operators(root4)
+# non_operators(root4)
+puts find_operator(root4, "-")
+
+# print_infix(root4)
+# puts ""
+# print_prefix(root4)
+# puts ""
+# print_postfix(root4)