Python选择排序、冒泡排序、合并排序代码实例

前两天刚装了python 3.1.1, 禁不住技痒写点code。
1.选择排序

>>> def SelSort(L):
    length=len(L)
    for i in range(length-1):
        minIdx=i
        minVal=L[i]
        j=i+1
        while j<length:
            if minVal>L[j]:
                minIdx=j
                minVal=L[j]
            j=j+1
        L[i],L[minIdx]=L[minIdx],L[i]
    return L

2.冒泡排序

>>> def bubSort(L):
    swapped=True
    while swapped:
        swapped=False
        for i in range(len(L)-1):
            if L[i]>L[i+1]:
                L[i],L[i+1]=L[i+1],L[i]
                swapped=True
    return L

3.合并排序

>>> def merge(left,right):
    result=[]
    i,j=0,0
    while i<len(left) and j<len(right):
        if left[i]<=right[j]:
            result.append(left[i])
            i=i+1
        else:
            result.append(right[j])
            j=j+1
    result+=left[i:]
    result+=right[j:]
    return result

>>> def mergesort(L):
    if len(L) < 2:
        return L
    else:
        middle = int(len(L)/2)
        left = mergesort(L[:middle])
        right = mergesort(L[middle:])
        return merge(left, right)