二叉樹遍歷葛碧，遞歸法 Python 3 實(shí)現(xiàn)：
# 二叉樹遍歷
# 定義節(jié)點(diǎn)
class Node:
def __init__(self, key):
self.data = key
self.left = None
self.right = None
self.parent = None
"""二叉樹
0
/ \
1 2
/ \ / \
3 4 5 6
"""
# 遞歸前序遍歷 根-左-右 0 1 3 4 2 5 6
def recursive_preorder_traversal(root):
if root != None:
# 打印根節(jié)點(diǎn)
print(root.data)
# 遍歷左子樹
left = root.left
if left != None:
recursive_preorder_traversal(left)
# 遍歷右子樹
right = root.right
if root.right != None:
recursive_preorder_traversal(right)
# 遞歸中序遍歷 左-根-右 3 1 4 0 5 2 6
def recursive_inorder_traversal(root):
if root != None:
# 遍歷左子樹
left = root.left
if left != None:
recursive_inorder_traversal(left)
# 打印根節(jié)點(diǎn)
print(root.data)
# 遍歷右子樹
right = root.right
if right != None:
recursive_inorder_traversal(right)
# 遞歸后序遍歷 左-右-中 3 4 1 5 6 2 0
def recursive_postorder_traversal(root):
if root != None:
# 遍歷左子樹
left = root.left
if left != None:
recursive_postorder_traversal(left)
# 遍歷右子樹
right = root.right
if right != None:
recursive_postorder_traversal(right)
# 打印根節(jié)點(diǎn)
print(root.data)
if __name__ == '__main__':
# 構(gòu)建二叉樹
root = Node(0)
node1 = Node(1)
node2 = Node(2)
node3 = Node(3)
node4 = Node(4)
node5 = Node(5)
node6 = Node(6)
root.left = node1
node1.parent = root
root.right = node2
node2.parent = root
node1.left = node3
node3.parent = node1
node1.right = node4
node4.parent = node1
node2.left = node5
node5.parent = node2
node2.right = node6
node6.parent = node2
recursive_preorder_traversal(root)
recursive_inorder_traversal(root)
recursive_postorder_traversal(root)
