Swift: Playgrounds are Worthwhile for LeetCode

I've often used creating a Command-line Mac OS application to complete LeetCode problems. This means that I've been able to use breakpoints in my answers and make sure that I'm thinking in a more strategic way.

But why don't I use Playgrounds?

The main reason is understanding what setup is required. This article is here to explain how to setup playgrounds, and guide you through the process.

The supporting video is @https://youtu.be/-LdOFoqnpkU.

Setting up Playgrounds

In order to use testing in Playgrounds, we need to import XCTest and create a class that conforms to the XCTestCase protocol, and then run className.defaultTestSuite.run().

We need an example in order to see this properly, so in steps LeetCode.

The problem

LeetCode has a problem: 1619

So the problem is 1619. Mean of Array After Removing Some Elements. This problem asks us to remove the smallest 5% and largest 5% of elements, and then calculate the mean.

However, one wrinkle in this is we need to make sure that the accuracy is within 10E-5, maning we need to use the accuracy parameter of XCTAssertEqual.

This leads us to the following solution:

import UIKit
import XCTest

class Solution {
    func trimMean(_ arr: [Int]) -> Double {
        let count = arr.count
        let stdArr = arr.sorted()
        let fivePercent = count / 20
        var sum = 0
        for i in fivePercent..<(count - fivePercent) {
            sum += stdArr[i]
        }
        return Double(sum) / Double(count - 2 * fivePercent)
    }
}

class Tests: XCTestCase {
    var solution = Solution()

    func test1() {
        XCTAssertEqual(solution.trimMean([1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3]), 2.00000, accuracy: 0.00001)
    }

    func test2() {
        XCTAssertEqual(solution.trimMean([6,2,7,5,1,2,0,3,10,2,5,0,5,5,0,8,7,6,8,0]), 4.00000, accuracy: 0.00001)
    }

    func test3() {
        XCTAssertEqual(solution.trimMean([6,0,7,0,7,5,7,8,3,4,0,7,8,1,6,8,1,1,2,4,8,1,9,5,4,3,8,5,10,8,6,6,1,0,6,10,8,2,3,4]), 4.77778, accuracy: 0.00001)
    }

    func test4() {
        XCTAssertEqual(solution.trimMean([9,7,8,7,7,8,4,4,6,8,8,7,6,8,8,9,2,6,0,0,1,10,8,6,3,3,5,1,10,9,0,7,10,0,10,4,1,10,6,9,3,6,0,0,2,7,0,6,7,2,9,7,7,3,0,1,6,1,10,3]), 5.27778, accuracy: 0.00001)
    }

    func test5() {
        XCTAssertEqual(solution.trimMean([4,8,4,10,0,7,1,3,7,8,8,3,4,1,6,2,1,1,8,0,9,8,0,3,9,10,3,10,1,10,7,3,2,1,4,9,10,7,6,4,0,8,5,1,2,1,6,2,5,0,7,10,9,10,3,7,10,5,8,5,7,6,7,6,10,9,5,10,5,5,7,2,10,7,7,8,2,0,1,1]), 5.29167, accuracy: 0.00001)
    }
}

Tests.defaultTestSuite.run()

Conclusion

I'm actually not that much of a big fan about Swift Playgrounds, but that might well be because I'm caught on a 2-core Mac so it could well be that it is just a little slow on my machine.

If you are interested in LeetCode problems I've plenty more content, so I hope that this is just one of my articles that you end up reading!

I hope this article has really helped you out!

If you've any questions, comments or suggestions please hit me up on Twitter