设二叉树采用二叉链表存储,设计递归算法实现二叉树中所有结点的左右孩子交换。
时间: 2024-05-10 10:02:12 浏览: 9
算法思路:
1. 如果二叉树为空,直接返回;
2. 如果二叉树不为空,交换当前节点的左右孩子;
3. 递归交换当前节点的左子树和右子树。
代码实现:
```python
class TreeNode:
def __init__(self, val):
self.val = val
self.left = None
self.right = None
def swapChildren(root):
if not root:
return
root.left, root.right = root.right, root.left
swapChildren(root.left)
swapChildren(root.right)
```
测试样例:
```python
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)
swapChildren(root)
# 遍历交换后的二叉树
def preorder(root):
if not root:
return
print(root.val, end=' ')
preorder(root.left)
preorder(root.right)
preorder(root) # 1 3 2 7 6 5 4
```