Initial data commit

Task/Tree-traversal/CoffeeScript/tree-traversal.coffee

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+# In this example, we don't encapsulate binary trees as objects; instead, we have a
+# convention on how to store them as arrays, and we namespace the functions that
+# operate on those data structures.
+binary_tree =
+  preorder: (tree, visit) ->
+    return unless tree?
+    [node, left, right] = tree
+    visit node
+    binary_tree.preorder left, visit
+    binary_tree.preorder right, visit
+
+  inorder: (tree, visit) ->
+    return unless tree?
+    [node, left, right] = tree
+    binary_tree.inorder left, visit
+    visit node
+    binary_tree.inorder right, visit
+
+  postorder: (tree, visit) ->
+    return unless tree?
+    [node, left, right] = tree
+    binary_tree.postorder left, visit
+    binary_tree.postorder right, visit
+    visit node
+
+  levelorder: (tree, visit) ->
+    q = []
+    q.push tree
+    while q.length > 0
+      t = q.shift()
+      continue unless t?
+      [node, left, right] = t
+      visit node
+      q.push left
+      q.push right
+
+do ->
+  tree = [1, [2, [4, [7]], [5]], [3, [6, [8],[9]]]]
+  test_walk = (walk_function_name) ->
+    output = []
+    binary_tree[walk_function_name] tree, output.push.bind(output)
+    console.log walk_function_name, output.join ' '
+  test_walk "preorder"
+  test_walk "inorder"
+  test_walk "postorder"
+  test_walk "levelorder"