https://github.com/trekhleb/javascript-algorithms/blob/master/src/algorithms/sets/cartesian-product/cartesianProduct.js#L8

I think it makes more sense to return an empty array

// invalid input return null or throw an error
if (!setA || !setB) {
    return null;
}
if (!setA.length || !setB.length) {
    return []; 
}
// or do nothing since the for loop will not trigger anyway

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

Hey Yangshun,
Thanks for the great list of guides!

I found the explanation for Snake game bit difficult to follow and I came across this interesting and better explanantion here https://www.youtube.com/watch?v=AaGK-fj-BAM

Contributing.md doesn't doesn't appear to contain any actual guidlines, and the link only leads back to the same document: Java/CONTRIBUTING.md.

Is there a reason why in travis CI config the command black --check . || true is run? I don't see the point in checking if files needs to be reformatted if it's just going to be ignored anyways.

Currently running black --line-length 127 --check . -> 399 files would be reformatted, 74 files would be left unchanged.

In additio

There are 2 places we are using BufferBlock<T> today:

https://github.com/dotnet/machinelearning/blob/b7db4fa475ba4bd52824eb98bbf5f5bf4a0a6f7a/src/Microsoft.ML.Data/Transforms/RowShufflingTransformer.cs#L486-L487

https://github.com/dotnet/machinelearning/blob/b7db4fa475ba4bd52824eb98bbf5f5bf4a0a6f7a/src/Microsoft.ML.Sweeper/AsyncSweeper.cs#L171

We should consider replacing this depende

首先，十分欢迎你来给 OI WIki 开 issue，在提交之前，请花时间阅读一下这个模板的内容，谢谢合作！

• 希望添加的是什么？

git 使用指南

• 英文叫什么？

git-guidebook

• 有什么参考资料？

https://git-scm.com/docs
https://git-scm.com/book/zh/v2

issue 标题请写为 'add ' + 要添加的内容

然后可以在 htc 里 link 一下。（我刚开始写 Wiki 的时候就不知道怎么做到“一个 pr 只干一件事”）

I create leetcode directory. You can contribute solution for Leetcode algorithm by C language.
Good practice coding :)
Please put some comment for explanation. It helps other people understand your algorithm better

Add quickselect algorithm. Quickselect is a selection algorithm to find the kth smallest element in an unordered list.

steps to reproduce

Write a loop, from 1 to 80000, each time add a random int to the max heap.

In theory it takes very little time(NlogN, N=80000, <1sec ), but the program does take a long time.

I'v also tested the BinaryHeap in https://github.com/SolutionsDesign/Algorithmia, it performs well, so it is probably due to the bad algorithm.

golangci-lint run --no-config searches

##[error]searches/binary_search.go:20:6: `iterBinarySearch` is unused (deadcode)
func iterBinarySearch(array []int, target int, lowIndex int, highIndex int) int {
     ^
##[error]searches/binary_search.go:6:6: func `binarySearch` is unused (unused)
func binarySearch(array []int, target int, lowIndex int, highIndex int) int {
     ^