Swift 归并排序

用Swift写的一个归并排序算法(递归法)

func Merge(sourceArray: NSMutableArray,tempArray: NSMutableArray,startIndex: Int,midindex: Int,endindex: Int) {
    var i = startIndex
    var j = midindex + 1
    var k = startIndex
        
    while(i != midindex+1 && j != endindex+1) {
        let one = sourceArray[i] as! Int
        let two = sourceArray[j] as! Int
        if one >= two {
            tempArray.insertObject(sourceArray[j],atIndex: k)
            j += 1
            k += 1
        }else {
            tempArray.insertObject(sourceArray[i],atIndex: k)
            i += 1
            k += 1
        }
    }
    while(i != midindex+1) {
        tempArray.insertObject(sourceArray[i],atIndex: k)
        i += 1
        k += 1
    }
    while(j != endindex+1) {
        tempArray.insertObject(sourceArray[j],atIndex: k)
        j += 1
        k += 1
    }
        
    for i in startIndex...endindex {
        sourceArray.replaceObjectAtIndex(i,withObject: tempArray[i])
    }
}
    
func MergeSort(sourceArray: NSMutableArray,endindex: Int) {
    var midindex = 0
    if startIndex < endindex {
        midindex = (startIndex + endindex)/2
        MergeSort(sourceArray,tempArray: tempArray,startIndex: startIndex,endindex: midindex)
        MergeSort(sourceArray,startIndex: midindex+1,endindex: endindex)
        Merge(sourceArray,midindex: midindex,endindex: endindex)
    }
}

从小到大排列。