Symmetric Tree

寒流來無聊窩在家裡寫 leetcode ，遇到了 101. Symmetric Tree，題目大意就是要判斷一棵二元樹是不是「對稱的」？一開始就想先把所有節點用 BFS 全部都列出來成一個 list，然後再根據二元樹的節點數一定會呈現「1+2+4+8+...」的模式、來把 list 切成 sublist。如果每個 sublist 都呈現對稱，就代 …

Iterative — Easy : https://leetcode.com/problems/symmetric-tree/ Recursive — Medium [ very important and intuitive] Hint : 1. A Tree is symmetric to itself. So if you implement a function which accepts two trees to check for symmetry, you can start the first call of the function with symmetric(root, root). Problem Statement: …

Question: 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 You may view the full question here. Approach 2: Let’s quickly…

Question: 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 You may view the full question here. Approach 1: Starting with…

This is a very interesting one question when you can approach it with either queue and stack data structure. Most of the time, queue is not working well with stack (maybe just my opinion, never mind). …