tree_0.svg

堆栈实现

  1. def stack_print(root):
  2.     if not root:
  3.         return
  4.     stack1 = []
  5.     stack2 = []
  6.     result = []
  8.     node = root
  9.     stack1.append(node)
  11.     while stack1:
  12.         node = stack1.pop()
  13.         if node.left:
  14.             stack1.append(node.left)
  15.         if node.right:
  16.             stack1.append(node.right)
  17.         stack2.append(node)
  19.     while stack2:
  20.         result.append(stack2.pop().val)
  22.     return result

递归实现

  1. def recursive_print(root):
  2.     result = []
  4.     def postorder(root):
  5.         if not root:
  6.             return
  8.         postorder(root.left)
  9.         postorder(root.right)
  10.         result.append(root.val)
  12.     postorder(root)
  14.     return result