算法回顾

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回顾一下4个基本算法:冒泡,选择,插入,快速

冒泡算法

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def bubble_sort(arr):
    length = len(arr)
    for i in range(1,length+1):
        for j in range(1,length-i+1):
            if arr[j-1]>arr[j]:
                arr[j-1],arr[j] = arr[j],arr[j-1]
                
    return arr

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选择排序

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def  select_sort(arr):
    length = len(arr)
    for i in range(length):
        for j in range(i+1,length):
            if arr[i]>arr[j]:
                arr[i],arr[j] = arr[j],arr[i]
    return arr

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插入排序

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# 插入排序,是跟前一个比较 比前一个小就往前移动
def insert_sort(arr):
    length = len(arr)
  
    for i in range(1,length):
        loop_index = i
        while loop_index>0 and arr[loop_index-1]>arr[loop_index]:
            count+=1
            arr[loop_index-1] ,arr[loop_index] = arr[loop_index],arr[loop_index-1]
            loop_index -=1
  
    return arr

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快速排序

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# 快速排序

def quick_sort(arr):
   
    length = len(arr)
    if length <= 1:
        return arr
    else:
        middle = arr.pop()
        bigs,smalls = [],[]
        for i in arr:
            
            if i <middle:
                smalls.append(i)
            else:
                bigs.append(i)
        return quick_sort(smalls) + [middle] + quick_sort(bigs)

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