SwiftyAlgos: Merge Sort

mergeSort.swift

import UIKit

// Merge sort in Swift

// Split arrays

func mergeSort(array: [Int]) -> [Int] {
    
    guard array.count > 1 else {
        return array
    }
    
    let leftArray = Array(array[0..<array.count/2])
    let rightArray = Array(array[array.count/2..<array.count])
    
    return merge(leftArray: mergeSort(array: leftArray), rightArray: mergeSort(array: rightArray))
}

// mergeArrays

func merge(leftArray: [Int], rightArray: [Int]) -> [Int] {
    
    var mergeList = [Int]()
    var left = leftArray
    var right = rightArray
    
    while left.count > 0 && right.count > 0 {
        if left.first! < right.first! {
            mergeList.append(left.removeFirst())
        } else {
            mergeList.append(right.removeFirst())
        }
    }

    return mergeList + left + right
}

var numbers = [Int]()

for _ in 0..<50 {
    numbers.append(Int(arc4random_uniform(UInt32(1000))))
}

let sorted = mergeSort(array: numbers)

print(numbers)
print()
print(sorted)