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class TreeNode:
"""节点类"""
def __init__(self, mid, left=None, right=None):
self.mid = mid
self.left = left
self.right = right
# 树类
class Tree:
"""树类"""
def __init__(self, root=None):
self.root = root
def add(self, item):
# 将要添加的数据封装成一个node结点
node = TreeNode(item)
if not self.root:
self.root = node
return
queue = [self.root]
while queue:
cur = queue.pop(0)
if not cur.left:
cur.left = node
return
else:
queue.append(cur.left)
if not cur.right:
cur.right = node
return
else:
queue.append(cur.right)
tree = Tree()
tree.add(0)
tree.add(1)
tree.add(2)
tree.add(3)
tree.add(4)
tree.add(5)
tree.add(6)
在上述树类代码基础上加遍历函数，基于递归实现。
先序遍历：
先序遍历结果是：0 -> 1 -> 3 -> 4 -> 2 -> 5 -> 6
# 先序遍历
def preorder(self, root, result=[]):
if not root:
return
result.append(root.mid)
self.preorder(root.left, result)
self.preorder(root.right, result)
return result
print("先序遍历")
print(tree.preorder(tree.root))
"""
先序遍历
[0, 1, 3, 4, 2, 5, 6]
"""
中序遍历：
中序遍历结果是：3 -> 1 -> 4 -> 0 -> 5 -> 2 -> 6
# 中序遍历
def inorder(self, root, result=[]):
if not root:
return result
self.inorder(root.left, result)
result.append(root.mid)
self.inorder(root.right, result)
return result
print("中序遍历")
print(tree.inorder(tree.root))
"""
中序遍历
3, 1, 4, 0, 5, 2, 6]
"""
后续遍历
后序遍历结果是：3 -> 4 -> 1 -> 5 -> 6 -> 2 -> 0
# 后序遍历
def postorder(self, root, result=[]):
if not root:
return result
self.postorder(root.left, result)
self.postorder(root.right, result)
result.append(root.mid)
return result
print("后序遍历")
print(tree.postorder(tree.root))
"""
后序遍历
[3, 4, 1, 5, 6, 2, 0]
"""
