Quick Sort Algorithm

quicksort.swift

var myarray4 = [4,6,2,7,7,3,5]
func quickSort(array: inout [Int], startIndex: Int, endIndex: Int) {
    
    if startIndex >= endIndex {
        return
    }
    
    let pivot = partition(array: &array, startIndex: startIndex, endIndex: endIndex)
    quickSort(array: &array, startIndex: startIndex, endIndex: pivot-1)
    quickSort(array: &array, startIndex: pivot+1, endIndex: endIndex)
}

func partition(array: inout [Int], startIndex: Int, endIndex: Int) -> Int {
    var q = startIndex
    for index in startIndex..<endIndex {
        if array[index] < array[endIndex] {
            array.swapAt(q, index)
            q += 1
        }
    }
    array.swapAt(q, endIndex)
    
    return q
}

quickSort(array: &myarray4, startIndex: 0, endIndex: 6)
print(myarray4)