Tree

# tree - preorder

tree = [('a', [('b', [('d', []),

 ('e', [])]),

  ('c', [('f', [])])])]

def preorder(tree):

stack = [tree[0]]

output = []

while stack:

value, children = stack.pop()

output.append(value)

stack.extend(reversed(children))

return output

print(preorder(tree))

# 결과

['a', 'b', 'd', 'e', 'c', 'f']

# tree - preorder

tree = [('a', [('b', [('d', []),

 ('e', [])]),

  ('c', [('f', [])])])]

from collections import deque

def levelorder(tree):

queue = deque([tree[0]])

output = []

while queue:

value, children = queue.popleft()

output.append(value)

queue.extend(children)

return output

print(levelorder(tree))

# 결과

['a', 'b', 'c', 'd', 'e', 'f']