Depth-first traversal
preorder(node)
if node == null then return
visit(node)
preorder(node.left)
preorder(node.right)
iterativePreorder(node)
parentStack = empty stack
while not parentStack.isEmpty() or node != null
if node != null then
parentStack.push(node)
visit(node)
node = node.left
else
node = parentStack.pop()
node = node.right
inorder(node)
if node == null then return
inorder(node.left)
visit(node)
inorder(node.right)
iterativeInorder(node)
parentStack = empty stack
while not parentStack.isEmpty() or node != null
if node != null then
parentStack.push(node)
node = node.left
else
node = parentStack.pop()
visit(node)
node = node.right
Postorder
postorder(node)
if node == null then return
postorder(node.left)
postorder(node.right)
visit(node)
iterativePostorder(node)
if node == null then return
nodeStack.push(node)
prevNode = null
while not nodeStack.isEmpty()
currNode = nodeStack.peek()
if prevNode == null or prevNode.left == currNode or prevNode.right == currNode
if currNode.left != null
nodeStack.push(currNode.left)
if currNode.right != null
nodeStack.push(currNode.right)
else if currNode.left == prevNode
if currNode.right != null
nodeStack.push(currNode.right)
else
visit(currNode)
nodeStack.pop()
prevNode = currNode
Breadth-first traversal:
levelorder(root)
q = empty queue
q.enqueue(root)
while not q.empty do
node := q.dequeue()
visit(node)
if node.left ≠ null
q.enqueue(node.left)
if node.right ≠ null
q.enqueue(node.right)
