2020-06-19 101. Symmetric Tree E

https://leetcode.com/problems/symmetric-tree/

My answer / AC

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {boolean}
 */
var isSymmetric = function(root) {
    let larr = [];
    let rarr = [];
    let dfs = function(node, arr, isLeft) {
        if(!node) {
            arr.push(null);
            return;
        }
        arr.push(node.val);
        if(isLeft) {
            dfs(node.left, arr, isLeft);
            dfs(node.right, arr, isLeft);
        } else {
            dfs(node.right, arr, isLeft);
            dfs(node.left, arr, isLeft);
        }
    }
    
    dfs(root, larr, true);
    dfs(root, rarr, false);
    return larr.toString() === rarr.toString();
};

Recap

和100类似的一道题，多了一个判断