LeetCode(101):Symmetric Tree

最新推荐文章于 2025-09-11 18:44:42 发布

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最新推荐文章于 2025-09-11 18:44:42 发布

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文章标签：数据结构与算法

原文链接：http://www.cnblogs.com/Lewisr/p/5232165.html

本文详细阐述了如何使用递归方法判断二叉树是否对称，并提供了相应的代码实现。包括递归和迭代两种解决方案。

Symmetric Tree:Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).

For example, this binary tree is symmetric:

But the following is not:

Note:
Bonus points if you could solve it both recursively and iteratively.

题意：判断二叉树是否对称。

思路：使用递归的方法同时对两棵子树进行递归判断。

代码：

public class Solution {
    public boolean isSymmetric(TreeNode root) {
        if(root==null) return true;
        return ifSymmetric(root.left,root.right);
    }
    public boolean ifSymmetric(TreeNode tree1,TreeNode tree2){
        if(tree1==null&&tree2==null)
            return true;
        else if(tree1==null || tree2==null)
            return false;
        if(tree1.val !=tree2.val)
            return false;
        else
        return (ifSymmetric(tree1.left,tree2.right) && ifSymmetric(tree1.right,tree2.left));
    }
}