对称二叉树

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题目类型: Tree

相关题目:

• 100. 相同的树

题目

给定一个二叉树, 检查它是否是镜像对称的.

示例

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

题解

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
//  * @return {boolean}
 */
var isMirror = function (p, q) {
  if (p === null && q === null) return true
  if (p === null || q === null) return false

  return (
    p.val === q.val && isMirror(p.left, q.right) && isMirror(p.right, q.left)
  )
}

var isSymmetric = function (root) {
  return isMirror(root, root)
}