排序算法＜Python＞

1. 冒泡排序
   
   

   def bubble_sort(li):
       for i in range(len(li)-1):
           ischanged=True
           for j in range(len(li)-i-1):
               if j+1<=len(li) and li[j]>li[j+1]:
                   li[j],li[j+1]=li[j+1],li[j]
                   ischanged=False
           if ischanged:
               return

2. 快排

   def partition(li,left,right):
       tmp=li[left]
       while left<right:
           while left<right and li[right]>=tmp:
               right-=1
           li[left] = li[right]
           while left<right and li[left]<=tmp:
               left+=1
           li[right]=li[left]
       li[left]=tmp
       return left
   def _quick_sort(li,left,right):
       if left<right:
           mid=partition(li,left,right)
           _quick_sort(li,left,mid)
           _quick_sort(li,mid+1,right)

3. 堆排序

   def sift(li,low,high):
       i=low
       j=2*i+1
       tmp=li[i]
       while j<=high:
           if j+1<=high and li[j+1]>li[j]:
               j=j+1
           if tmp<li[j]:   #注意细节，li[j]大于tmp
               li[i]=li[j]
               i=j
               j=2*i+1
           else:
               break
       li[i] = tmp
   
   def heap_sort(li):
       '''
       help me
       '''
       n=len(li)-1
       for i in range((n-1)//2,-1,-1):
           sift(li,i,n)
       for i in range(n,-1,-1):
           li[i],li[0]=li[0],li[i]
           sift(li,0,i-1)

4. 归并排序