• We have BFS and DFS images in both Breadth First Traversal and Depth First Traversal. We should have illustrations in the respective sections.

集合 S 包含从1到 n 的整数。不幸的是，因为数据错误，导致集合里面某一个元素复制了成了集合里面的另外一个元素的值，导致集合丢失了一个整数并且有一个元素重复。

给定一个数组 nums 代表了集合 S 发生错误后的结果。你的任务是首先寻找到重复出现的整数，再找到丢失的整数，将它们以数组的形式返回。

示例 1:

输入: nums = [1,2,2,4]
输出: [2,3]
注意:

给定数组的长度范围是 [2, 10000]。
给定的数组是无序的。

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/set-mismatch

🚀 Feature Proposal

Adding leading zero in the question number will be an awesome feature for file explorer to sort files by the name.

Given a blacklist B containing unique integers from [0, N), write a function to return a uniform random integer from [0, N) which is NOT in B.

Optimize it such that it minimizes the call to system’s Math.random().

Note:

1. 1 <= N <= 1000000000
2. 0 <= B.length < min(100000, N)
3. [0, N) does NOT include N. See [interval notation](https://en.wikipedia.org/wiki/Interval_\

Add new sections by GitbookIO editor is quite simple, but sometimes you may forget to add sections in SUMMARY.md.

It is easy to parse the title of source .md files and add it to the appropriate chapter position. I will implement this feature with Python.

It'll be good to add an introduction into the readme for the basic information of the repo, such as where are the problems coming from, how do you pick problems into this repo, etc.