0101. Symmetric Tree

101. Symmetric Tree #

题目 #

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

For example, this binary tree [1,2,2,3,4,4,3] is symmetric:


    1
   / \
  2   2
 / \ / \
3  4 4  3

But the following [1,2,2,null,3,null,3] is not:


    1
   / \
  2   2
   \   \
   3    3

Note:

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

题目大意 #

这一题要求判断 2 颗树是否是左右对称的。

解题思路 #

  • 这道题是几道题的综合题。将根节点的左字数反转二叉树,然后再和根节点的右节点进行比较,是否完全相等。
  • 反转二叉树是第 226 题。判断 2 颗树是否完全相等是第 100 题。

代码 #


package leetcode

/**
 * Definition for a binary tree node.
 * type TreeNode struct {
 *     Val int
 *     Left *TreeNode
 *     Right *TreeNode
 * }
 */
func isSymmetric(root *TreeNode) bool {
	if root == nil {
		return true
	}
	return isSameTree(invertTree(root.Left), root.Right)
}


⬅️上一页

下一页➡️

Calendar Sep 6, 2020
Edit Edit this page
本站总访问量:  次 您是本站第  位访问者