二叉树的基本操作代码
时间: 2023-12-10 20:34:10 浏览: 46
以下是二叉树的基本操作代码,包括手动创建二叉树、遍历二叉树、获取节点个数、获取叶子节点个数、获取二叉树高度、检测元素是否存在、层序遍历和判断是否为完全二叉树:
```python
# 定义二叉树节点类
class TreeNode:
def __init__(self, val=0, left=None, right=None):
self.val = val
self.left = left
self.right = right
# 手动创建二叉树
def create_tree():
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.left.right = TreeNode(5)
root.right.left = TreeNode(6)
root.right.right = TreeNode(7)
return root
# 前序遍历
def preorder_traversal(root):
if not root:
return []
res = []
stack = [root]
while stack:
node = stack.pop()
res.append(node.val)
if node.right:
stack.append(node.right)
if node.left:
stack.append(node.left)
return res
# 中序遍历
def inorder_traversal(root):
if not root:
return []
res = []
stack = []
node = root
while stack or node:
while node:
stack.append(node)
node = node.left
node = stack.pop()
res.append(node.val)
node = node.right
return res
# 后序遍历
def postorder_traversal(root):
if not root:
return []
res = []
stack = [root]
while stack:
node = stack.pop()
res.append(node.val)
if node.left:
stack.append(node.left)
if node.right:
stack.append(node.right)
return res[::-1]
# 获取节点个数(迭代)
def get_node_count_iteration(root):
if not root:
return 0
count = 0
stack = [root]
while stack:
node = stack.pop()
count += 1
if node.left:
stack.append(node.left)
if node.right:
stack.append(node.right)
return count
# 获取节点个数(递归)
def get_node_count_recursion(root):
if not root:
return 0
return 1 + get_node_count_recursion(root.left) + get_node_count_recursion(root.right)
# 获取叶子节点个数(迭代)
def get_leaf_count_iteration(root):
if not root:
return 0
count = 0
stack = [root]
while stack:
node = stack.pop()
if not node.left and not node.right:
count += 1
if node.left:
stack.append(node.left)
if node.right:
stack.append(node.right)
return count
# 获取叶子节点个数(递归)
def get_leaf_count_recursion(root):
if not root:
return 0
if not root.left and not root.right:
return 1
return get_leaf_count_recursion(root.left) + get_leaf_count_recursion(root.right)
# 获取二叉树高度
def get_tree_height(root):
if not root:
return 0
return max(get_tree_height(root.left), get_tree_height(root.right)) + 1
# 检测元素是否存在
def check_element_exist(root, val):
if not root:
return False
if root.val == val:
return True
return check_element_exist(root.left, val) or check_element_exist(root.right, val)
# 层序遍历
def level_order_traversal(root):
if not root:
return []
res = []
queue = [root]
while queue:
level = []
for i in range(len(queue)):
node = queue.pop(0)
level.append(node.val)
if node.left:
queue.append(node.left)
if node.right:
queue.append(node.right)
res.append(level)
return res
# 判断是否为完全二叉树
def is_complete_tree(root):
if not root:
return True
queue = [root]
flag = False
while queue:
node = queue.pop(0)
if node.left:
if flag:
return False
queue.append(node.left)
else:
flag = True
if node.right:
if flag:
return False
queue.append(node.right)
else:
flag = True
return True
```