Difficult:Medium

題目

Given two integer arrays preorder and inorder where preorder is the preorder traversal of a binary tree and inorder is the inorder traversal of the same tree, construct and return the binary tree.

Difficult:Easy

題目

Given the root of a binary tree, return its maximum depth.

A binary tree’s maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Difficult:Medium

題目

Given the root of a binary tree, return the zigzag level order traversal of its nodes’ values. (i.e., from left to right, then right to left for the next level and alternate between).

Difficult:Medium

題目

Given the root of a binary tree, return the level order traversal of its nodes’ values. (i.e., from left to right, level by level).

前言

SOLID 是5大原則的簡稱，分別為：
S = Single-responsibility principle (SRP) = 單一職責原則
O = Open–closed principle (OCP) = 開放封閉原則
L =Liskov substitution principle (LSP) = 里氏替換原則
I = Interface segregation principle (ISP) = 介面隔離原則
D = Dependency inversion principle (DIP) = 依賴反向原則