更新：《24点》APP——提示功能实现

背景

商店里所有24点 APP 的一个付费功能是提示的获取，会通过限制提示次数，超出次数后观看广告或者购买来解锁额外次数。比如：

Algorithem_Matrix

题目

Given an m x n binary matrix mat, return the distance of the nearest 0 for each cell.

The distance between two adjacent cells is 1.

Algorithem_PermutationInString

Given two strings s1 and s2, return true if s2 contains a permutation of s1, or false otherwise.

In other words, return true if one of s1’s permutations is the substring of s2.

Algorithem_ReverseLinkedList

Given the head of a singly linked list, reverse the list, and return the reversed list.

Algorithem_MergeTwoSortedLists

You are given the heads of two sorted linked lists list1 and list2.

Merge the two lists in a one sorted list. The list should be made by splicing together the nodes of the first two lists.

Return the head of the merged linked list.

Algorithem_Merge Two Binary Trees

You are given two binary trees root1 and root2.

Imagine that when you put one of them to cover the other, some nodes of the two trees are overlapped while the others are not. You need to merge the two trees into a new binary tree. The merge rule is that if two nodes overlap, then sum node values up as the new value of the merged node. Otherwise, the NOT null node will be used as the node of the new tree.

Algorithem_Populating Next Right Pointers in Each Node

You are given a perfect binary tree where all leaves are on the same level, and every parent has two children. The binary tree has the following definition:

iOS长截图

背景

Twitter 上看到TaioApp的作者说，iOS 系统有支持长截图的API——UIScreenshotService，从 iOS 13开始就可以使用，下午的时候就在自己的 APP 中体验了一下。

733. Algorithem_Max Area of Island

You are given an m x n binary matrix grid. An island is a group of 1’s (representing land) connected 4-directionally (horizontal or vertical.) You may assume all four edges of the grid are surrounded by water.

733. Flood Fill

An image is represented by an m x n integer grid image where image[i][j] represents the pixel value of the image.