func example(str: String, isAction: Bool = true, action: () -> Void) {
    print("---------\(str), isAction: \(isAction)---------")
    
    if isAction {
        action()
    }
}

func createRandomArray(numberOfElements: Int = 10) -> [Int] {
    var randomIntInArray: [Int] = [Int]()
    while randomIntInArray.count != numberOfElements {
        let popRandomValue = Int(arc4random_uniform(11))
        randomIntInArray.append(popRandomValue)
    }
    return randomIntInArray
}

example(str: "Merge Sort", isAction: true) {
    func mergeSort<T: Comparable>(data: [T]) -> [T] {
        print(data)
        guard data.count > 1 else { return data }
        let middle = data.count / 2
        let left = mergeSort(data:Array(data[..<middle]))
        let right = mergeSort(data:Array(data[middle...]))
        print("middle: \(middle), left:\(left), right:\(right)")
        return merge(left, right)
        
    }    
    func merge<T: Comparable>(_ left: [T], _ right: [T]) -> [T] {
        // 1
        var leftIndex = 0
        var rightIndex = 0
        // 2
        var result: [T] = []
        // 3
        while left.count > leftIndex && right.count > rightIndex  {
            let leftElement = left[leftIndex]
            let rightElement = right[rightIndex]
            print("leftcount,leftIndex: \(left.count):\(leftIndex), rightcount,rightIndex: \(right.count):\(rightIndex), left,leftElement: \(left):\(leftElement), right,rightElement: \(right):\(rightElement)  Result\(result)")
            // 4
            if leftElement < rightElement {
                result.append(leftElement)
                leftIndex += 1
                print("leftcount,leftIndex: \(left.count):\(leftIndex), rightcount,rightIndex: \(right.count):\(rightIndex), left,leftElement: \(left):\(leftElement), right,rightElement: \(right):\(rightElement)  Result\(result)")
                
            } else if leftElement > rightElement {
                result.append(rightElement)
                rightIndex += 1
                print("leftcount,leftIndex: \(left.count):\(leftIndex), rightcount,rightIndex: \(right.count):\(rightIndex), left,leftElement: \(left):\(leftElement), right,rightElement: \(right):\(rightElement)  Result\(result)")
            } else {
                result.append(leftElement)
                leftIndex += 1
                result.append(rightElement)
                rightIndex += 1
                print("leftcount,leftIndex: \(left.count):\(leftIndex), rightcount,rightIndex: \(right.count):\(rightIndex), left,leftElement: \(left):\(leftElement), right,rightElement: \(right):\(rightElement)  Result\(result)")
            }
        }
        
        // 5
        if leftIndex < left.count {
            result.append(contentsOf: left[leftIndex...])
            print("leftcount,leftIndex: \(left.count):\(leftIndex), rightcount,rightIndex: \(right.count):\(rightIndex), Result\(result)")
        }
        if rightIndex < right.count {
            result.append(contentsOf: right[rightIndex...])
            print("leftcount,leftIndex: \(left.count):\(leftIndex), rightcount,rightIndex: \(right.count):\(rightIndex), Result\(result)")
        }
        return result
    }
    let x = createRandomArray(numberOfElements: 10)
    print(mergeSort(data:x))
}