Question

题目内容

解题思路

递归。

代码实现

/**
 * Definition for a binary tree node.
 * class TreeNode {
 *     val: number
 *     left: TreeNode | null
 *     right: TreeNode | null
 *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
 *         this.val = (val===undefined ? 0 : val)
 *         this.left = (left===undefined ? null : left)
 *         this.right = (right===undefined ? null : right)
 *     }
 * }
 */

const isSymmetric = (root: TreeNode | null): boolean => {
  const check = (p: TreeNode | null, q: TreeNode | null): boolean => {
    if (!p && !q) return true;
    if (!p || !q) return false;
    return p.val === q.val && check(p.left, q.right) && check(p.right, q.left);
  };
  return check(root, root);
};