用 Python 编写程序检查给定的树是否为对称树

pythonserver side programmingprogramming更新于 2026/2/4 8:44:17

假设我们有一棵二叉树。我们必须检查这棵树是否为对称树。如果一棵树的镜像相同，则称其为对称树。从这两棵树来看，第一棵是对称的，但第二棵不是。

为了解决这个问题，我们将遵循以下步骤。

我们将递归调用以下步骤。该函数将为solve(root, root)
如果node1和node2为空，则返回true
如果node1或node2为空，则返回false
当node1.val = node2.val且solve(node1.left, node2.right)和solve(node1.right, node2.left)时返回true

让我们看看下面的实现以便更好地理解 −

示例

class TreeNode:
   def __init__(self, data, left = None, right = None):
      self.data = data
      self.left = left
      self.right = right
class Solution(object):
   def isSymmetric(self, root):
      return self.solve(root,root)
   def solve(self,node1,node2):
      if not node1 and not node2:
         return True
      if not node1 or not node2:
         return False
      return node1.data == node2.data and
self.solve(node1.left,node2.right) and
self.solve(node1.right,node2.left)
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(2)
root.left.left = TreeNode(3)
root.left.right = TreeNode(4)
root.right.left = TreeNode(4)
root.right.right = TreeNode(3)
ob1 = Solution()
print(ob1.isSymmetric(root))

输入

root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(2)
root.left.left = TreeNode(3)
root.left.right = TreeNode(4)
root.right.left = TreeNode(4)
root.right.right = TreeNode(3)