算法---排序
1.常见的时间复杂度(按耗费的时间排序,时间耗费越少效率越高)
O(1)<O(logn)<O(n)<O(nlogn)<O(n2)<O(n2logn)<O(n3)
循环减半就是(O(logn))
2.冒泡排序
li = [6,8,9,7,5,3]
def bubble_sort(li): for i in range(len(li)-1): for j in range(len(li)-i-1): if li[j] > li[j+1]: li[j], li[j+1] = li[j+1], li[j]
3.冒泡排序优化
def bubble_sort_1(li): for i in range(len(li)-1): exchange = False for j in range(len(li)-i-1): if li[j] > li[j+1]: li[j], li[j+1] = li[j+1], li[j] exchange = True if not exchange:#如果没有执行交换,说明已经是有序状态了,无需继续排序了 return
4.快速排序
data = [7,9,5,3,1,4,89] def partition(data, left, right): left = 0 right = len(data) tmp = data[left] while left < right: while left < right and data[right] >= tmp: right -= 1 data[left] = data[right] while left < right and data[left] <= tmp: left += 1 data[right] = data[left] data[left] = tmp return left