Swift 4 Migration

[kelvinlauKL]

Update

Thanks everyone for helping out with the migration! Another year, another migration complete :]

---

It's that time of the year again. Swift 4 is imminent, so it's time to begin migration. Swift 3 to Swift 4 has been relatively painless compared to other years, so things should go rather smoothly!

Migration Procedure:

1. Choose a topic below that hasn't been checked off
2. Check the pull requests to see if anyone is working on your chosen topic
3. Make a pull request to let others know that you're currently working on your chosen topic

• Add the following code snippet at the top of each playground file:

// last checked with Xcode 9.0b4
#if swift(>=4.0)
   print("Hello, Swift 4!")
#endif

• Make sure the code for the topic compiles correctly with the latest Xcode 9 beta (currently beta 4).
• Make sure that the README.md file reflects the updated playground

Current Progress

• AVL Tree
• All-Pairs Shortest Paths
• Array2D
• B-Tree
• Binary Search Tree
• Binary Search
• Binary Tree
• Bit Set
• Bloom Filter
• Bounded Priority Queue
• Boyer-Moore
• Breadth-First Search
• Brute-Force String Search
• Bubble Sort
• Bucket Sort
• Comb Sort
• Combinatorics
• Convex Hull
• Count Occurrences
• Counting Sort
• Depth-First Search
• Deque
• Dijkstra Algorithm
• DiningPhilosophers
• Fixed Size Array
• Fizz Buzz
• GCD
• Graph
• Hash Set
• Hash Table
• HaversineDistance
• Heap Sort
• Heap
• Huffman Coding
• Insertion Sort
• K-Means
• Karatsuba Multiplication
• Knuth-Morris-Pratt
• Kth Largest Element
• LRU Cache
• Linear Regression
• Linear Search
• Linked List
• Longest Common Subsequence
• Merge Sort
• Miller-Rabin Primality Test
• Minimum Edit Distance
• Minimum Spanning Tree (Unweighted)
• Minimum Spanning Tree
• MinimumCoinChange
• Monty Hall Problem
• Ordered Array
• Ordered Set
• Palindromes
• Priority Queue
• QuadTree
• Queue
• Quicksort
• Rabin-Karp
• Radix Sort
• Radix Tree
• Red-Black Tree
• Ring Buffer
• Rootish Array Stack
• Run-Length Encoding
• Segment Tree
• Select Minimum Maximum
• Selection Sampling
• Selection Sort
• Set Cover (Unweighted)
• Shell Sort
• Shortest Path (Unweighted)
• Shuffle
• Shunting Yard
• Single-source Shortest Paths(Weighted)
• Skip-List
• Slow Sort
• Stack
• Strassen Matrix Multiplication
• Ternary Search Tree
• Threaded Binary Tree
• Topological Sort
• Treap
• Tree
• Trie
• Two-Sum Problem
• Union-Find
• Z-Algorithm

[shabirjan]

Hi i want to contribute in this task. Please tell me the procedure to contribute in this Project.

[kelvinlauKL]

@shabirjan Cool. I've updated the issue to include the steps you'd want to do.

[bobdel]

There are no pull requests as of yet "claiming" items, correct? I was looking for an example of how to do one.

Also, I suggest adding the following to each playground. Either that, or just the comment, in the playground or the readme so its instantly obvious which items are up to date.

// last checked with Xcode 9.0b4
#if swift(>=4.0)
   print("Hello, Swift 4!")
#endif

[kelvinlauKL]

@bobdel That's actually a good idea!

[coolbnjmn]

I've claimed 2Sum with this PR: #513

@kelvinlauKL lmk if I need to fix up anything in that until it's ready (should be quite shortly, just didn't want any duplication of effort :D ).

[coolbnjmn]

@kelvinlauKL PR #513 is ready to go, I didn't put the #ifdef but I used it to just sanity check. I added the comment with the exact build number I used (beta4) to check. If this is all that's needed, I'll attack another soon but this one needed no changes. PR only added the comment that it was checked in Xcode9b4. Not sure if I'm missing something though, lmk!

[shabirjan]

@kelvinlauKL PR #516 claimed Bucketsort and is ready to go :)

[remlostime]

Bubble sort has no implementation. We are good to mark it as done.