1.冒泡排序,相邻位置比较大小,将比较大的(或小的)交换位置
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def maopao(a): for i in range ( 0 , len (a)): for j in range ( 0 , len (a) - i - 1 ): if a[j]>a[j + 1 ]: temp = a[j + 1 ] a[j + 1 ] = a[j] a[j] = temp #print(a) #print(a) print (a) |
2.选择排序,遍历选择一个最小的数与当前循环的第一个数交换
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def xuanze(a): for i in range ( 0 , len (a)): k = i temp = a[i] for j in range (i, len (a)): if a[j]<temp: temp = a[j] k = j a[k] = a[i] a[i] = temp print (a) |
3.快速排序:将子段的第一个元素做为中值,先从右向左遍历,如过比中值大high-1,如果比中值小,将这个值放到low那里。
然后从左向右开始遍历,如果左侧的比中值大,将他放到high那里。当low>=high时,将中值的值赋给low
(1.以下为参照公众号中的做法:
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a = [ 7 , 1 , 3 , 2 , 6 , 54 , 4 , 4 , 5 , 8 , 12 , 34 ] def sort(a,low,high): while low < high: temp = a[low] while low < high and a[high]> = temp: high = high - 1 a[low] = a[high] while low<high and a[low]<temp: low = low + 1 a[high] = a[low] a[low] = temp return low def quicksort(a,low,high): if low<high: middle = sort(a,low,high) quicksort(a,low,middle) quicksort(a,middle + 1 ,high) print (a) sort(a, 0 , len (a) - 1 ) quicksort(a, 0 , len (a) - 1 ) print (a) |
(2.以下是参照网上的做法:
在做快速排序时一直各种问题,是因为地柜那里没有考虑清楚,一直把low的值赋值为0了,实际上应该是不固定的low值,他每个子循环不定。
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''' 遇到问题没人解答?小编创建了一个Python学习交流群:531509025 寻找有志同道合的小伙伴,互帮互助,群里还有不错的视频学习教程和PDF电子书! ''' a = [ 7 , 1 , 3 , 2 , 6 , 54 , 4 , 4 , 5 , 8 , 12 , 34 ] def sort(a,low,high): while low < high: temp = a[low] while low < high and a[high]> = temp: high = high - 1 while low<high and a[high]<temp: a[low] = a[high] low = low + 1 a[high] = a[low] a[low] = temp return low def quicksort(a,low,high): if low<high: middle = sort(a,low,high) quicksort(a,low,middle) quicksort(a,middle + 1 ,high) print (a) sort(a, 0 , len (a) - 1 ) quicksort(a, 0 , len (a) - 1 ) print (a) |
4.插入排序:从左向右遍历,依次选取数值,从数值的左侧从右向左遍历,选择第一个比他小的数值的右侧插入该数值,其他数值依次向后赋值
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#插入排序 a = [ 7 , 1 , 3 , 2 , 6 , 54 , 4 , 4 , 5 , 8 , 12 , 34 ] for i in range ( 0 , len (a) - 1 ): temp = a[i + 1 ] j = i + 1 while j> = 0 and temp<a[j - 1 ]: j = j - 1 print (j) if j> = - 1 : k = i + 1 while k> = j: a[k] = a[k - 1 ] k = k - 1 print (a) a[j] = temp print (a) |
插入排序方法2,用到了列表的a.insert(1,2)和清楚a[2:3]=[],这样可以少用一个循环
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a = [ 7 , 1 , 3 , 2 , 6 , 54 , 4 , 4 , 5 , 8 , 12 , 34 ] for i in range ( 1 , len (a) - 1 ): temp = a[i] j = i - 1 while j> = 0 and temp< = a[j]: print (temp) j = j - 1 if j > = - 1 : a[i:i + 1 ] = [] a.insert(j + 1 ,temp) print (a) print (a) |
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原文链接:https://www.cnblogs.com/python960410445/p/15013047.html