python：实现几种排序算法

冒泡排序

比较相邻两个字符，如果左边大于右边，则交换位置，遍历一遍字符后，则最大的肯定在最右边；继续循环处理剩下的字符（最右边的不用再比较了，已经最大了）

代码实现：

def BubbleSort(sourceStr):
    l = list(sourceStr)
    cnt = len(l)-1

    while cnt >= 0:
        i = 0
        j = 0
        while i < cnt:
            j = i + 1
            if l[i] > l[j]:
                tmp = l[j]
                l[j] = l[i]
                l[i] = tmp
            i+=1
        cnt-=1
    return ''.join(l)

if __name__ == '__main__':
    myStr = '125694520'
    print(' Before Sort: %s \n After  Sort: %s' %(myStr,BubbleSort(myStr)) )

执行结果：

C:\Users\suneee\AppData\Local\Programs\Python\Python36\python.exe E:/wangjz/PyWorkSpace/LearnPython/test_order.py
 Before Sort: 125694520 
 After  Sort: 012245569

Process finished with exit code 0

选择排序

每次从字符串中选择最小的值，放到新的列表中，选完一个，原字符串就去掉最小的那个；直到选完，新的列表也组成了

代码实现：

def SelectSort(sourceStr):
    oldList = list(sourceStr)
    newList = []
    maxStr = ''
    while oldList!=[]:
        maxStr = min(oldList)
        newList.append(maxStr)
        oldList.remove(maxStr)
    return ''.join(newList)

if __name__ == '__main__':
    myStr = '125694520'
    # print(' Before Sort: %s \n After  Sort: %s' %(myStr,BubbleSort(myStr)) )
    print(' Before Sort: %s \n After  Sort: %s' %(myStr,SelectSort(myStr)) )

执行结果：

C:\Users\suneee\AppData\Local\Programs\Python\Python36\python.exe E:/wangjz/PyWorkSpace/LearnPython/test_order.py
 Before Sort: 125694520 
 After  Sort: 012245569

Process finished with exit code 0