xwrobelekx/codewarschallenges

Challenges I have solved from code wars.

CodeWars Code Challenges

This page represents my daily code challanges which focuse on:

• Swift programming language.
• Dart programming language (occasionally).

My current rank:

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Organization:

• There is one main playground which holds many sub folders.
• Each supfolder represents a new challenge.
• Originally they were numbered by days, then by dates, and now I just organize them by its title and difuculty raiting for clearer context.
• Each file has a title and kata rating (kyu) (8 being easiet, 1 being the hardest).

Each page contains:

• Brief description of a problem.
• My solution to a challenge.
• Some other clever solutions made by other users.
• XCTests.

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Playground page structure:

Section1: Title with link to the challenge, example, and my approach.

// Gravity flip - 8kyu
// Link: https://www.codewars.com/kata/5f70c883e10f9e0001c89673

// Objective: Given direction of ether Left (L) or Right (R) sort the array (a) in corresponding order.

// Example:
// 'R', [3, 2, 1, 2]      ->  [1, 2, 2, 3]
// 'L', [1, 4, 5, 3, 5 ]  ->  [5, 5, 4, 3, 1]

// My approach:
// 1. Switch on the direction
// 2. Base on the direction, use sorted(by:) function to sort element
// 3. Return those sorted elements or empty array if something goes wrong.

Section2: My solution.

// MARK: - My Solution

func flip(_ direction: String, _ a: [Int]) -> [Int] {
  switch direction {
    case "L":
    return a.sorted(by: >)
    case "R" :
    return a.sorted()
    
  default:
      return []
  }
}

Section3: Other Celever solutions.

// MARK: - Other Solutions:

 func flip2(_ direction: String, _ a: [Int]) -> [Int] {
    return a.sorted(by: direction == "L" ? (>) : (<))
 }
 
 func flip3(_ direction: String, _ a: [Int]) -> [Int] {
     return direction == "R" ? a.sorted() : a.sorted().reversed()
 }

Section4: Tests.

// MARK: - Tests

import XCTest

class GravityFlipTests: XCTestCase {
    
    func testRightFlip() {
        XCTAssertEqual(flip("R", [3, 2, 1, 2]), [1, 2, 2, 3])
        XCTAssertEqual(flip2("R", [3, 2, 1, 2]), [1, 2, 2, 3])
        XCTAssertEqual(flip3("R", [3, 2, 1, 2]), [1, 2, 2, 3])
    }
    
    func testLeftFlip() {
        XCTAssertEqual(flip("L", [1, 4, 5, 3, 5]), [5, 5, 4, 3, 1])
        XCTAssertEqual(flip2("L", [1, 4, 5, 3, 5]), [5, 5, 4, 3, 1])
        XCTAssertEqual(flip3("L", [1, 4, 5, 3, 5]), [5, 5, 4, 3, 1])
    }
    
    func testInvalid() {
        XCTAssertEqual(flip("X", []), [])
        XCTAssertEqual(flip2("X", []), [])
        XCTAssertEqual(flip3("X", []), [])
    }
    
}

GravityFlipTests.defaultTestSuite.run()

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