python算法

1.插入排序
def insert_sort(ls):
    for i in range(1,len(ls)):
        j = i
        while j >0 and ls[j-1] > ls[j]:
            tmp = ls[j]
            ls[j] = ls[j-1]
            ls[j-1] = tmp
            j -= 1


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2.冒泡排序
def bubble_sort(ls):
    n = len(ls)
    for j in range(1,n):
        for i in range(j,0-1):
            if ls[i-1] > ls[i]
                tmp = ls[i-1]
                ls[i-1] = ls[i]
                ls[i] = tmp


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3.快速排序
def quick_sort(ls):

    return ls if len(ls)<=1 else quick_sort([i for i in ls[1:] if i<=ls[0]]) +[ls[0]] + quick_sort([i for i in ls[1:] if i>ls[0]])

http://code.activestate.com/recipes/474088/     尾递归  @tail_call_optimized

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4.归并排序
def merge_sort(ls):
        if(len(ls) <= 1):  
            return ls
    left = merg_sort(ls[:len(ls)/2])
    right = merg_sort(ls[len(ls)/2:len(ls)])
    result = []
    while len(left) > 0 and len(right)> 0:
        if( left[0] > right[0]):
            result.append(right.pop(0))
        else:
            result.append(left.pop(0))
 
    if(len(left)>0): 
        result.extend(merg_sort(left))
    else: 
        result.extend(merg_sort(right))
    return result
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