用python实现归并排序

'''Created on 2017-1-6@author: admin'''from builtins import  range, intdef mergeSort(source,start,end):    if(start>=end):        return    middle=int((start+end)/2)    mergeSort(source, start, middle)    mergeSort(source, middle+1, end)    merge(source, start, end)def merge(source,start,end):    middle=int((start+end)/2)    sortedArray=[]    i,j=start,middle+1    while i<=middle:        if(j>end):break;        if(source[i]>source[j]):            sortedArray.append(source[j])            j=j+1        else:            sortedArray.append(source[i])            i=i+1    if(i<=middle):        for ii in range(i,middle+1):            sortedArray.append(source[ii]);    if(j<=end):        for jj in range(j,end+1):            sortedArray.append(source[jj])    x=0    for i in range(start,end+1):        source[i]=sortedArray[x]        x=x+1if __name__ == '__main__':    source=[4,1,9,2,8,7,3,6]    mergeSort(source,0,len(source)-1)    for i in range(0,len(source)):        print(source[i], end=',')