本文共 2691 字,大约阅读时间需要 8 分钟。
在这里插入代码片
def select_sort(items, *, cmp=lambda x1, x2: x1 > x2): items = items[:] n = len(items) for i in range(n): point = i # point指向最小值 for j in range(i+1, n): if cmp(items[point], items[j]): point = j if point != i: items[i], items[point] = items[point], items[i] return itemsnums3=[1,4,23,67,3,66,69,13]print('排序前:nums3', nums3) # 排序前:nums3 [1, 4, 23, 67, 3, 66, 69, 13]print('排序结果:', select_sort(nums3)) # 排序结果: [1, 3, 4, 13, 23, 66, 67, 69]print('排序后:nums3', nums3) # 排序后:nums3 [1, 4, 23, 67, 3, 66, 69, 13]
冒泡排序:通过不管是升序还是降序,每一次从开始遍历都需要两两比较,把这一轮遍历最大或者最小的值放在最后(冒泡)。下一轮遍历开始前时需要遍历的长度减1。
# 函数应该做到无副作用(调用函数后不影响原来的参数)def bubble_sort(items, *, cmp=lambda x, y: x > y): items = items[:]# 相当于深拷贝 n = len(items) for i in range(n - 1): swapped = False for j in range(n - 1 - i): if cmp(items[j], items[j + 1]): items[j], items[j + 1] = items[j + 1], items[j] swapped = True if not swapped: break return items nums = np.random.randint(1, 100, 8).tolist()print('排序前nums:', nums) # 排序前nums: [23, 81, 69, 46, 36, 11, 10, 16]print('排序结果:', bubble_sort(nums)) # 排序结果: [10, 11, 16, 23, 36, 46, 69, 81]print('排序后nums:',nums) # 排序后nums: [23, 81, 69, 46, 36, 11, 10, 16]
def merge(items1, items2): """将两个有序的列表合并成一个新的有序列表""" items3 = [] idx1, idx2 = 0, 0 while idx1 < len(items1) and idx2 < len(items2): a, b = items1[idx1], items2[idx2] if a <= b: items3.append(a) idx1 += 1 else: items3.append(b) idx2 += 1 items3 += items1[idx1:] items3 += items2[idx2:] return items3# nums1 = [12, 35, 41, 58, 67, 99]# nums2 = [10, 11, 20, 30, 40, 50]# merge(nums1, nums2) # [10, 11, 12, 20, 30, 35, 40, 41, 50, 58, 67, 99]def merge_sort(items): """归并排序""" if len(items) <= 1: return items[:] mid = len(items) // 2 left, right = items[:mid], items[mid:] return merge(merge_sort(left), merge_sort(right))nums3 = [1,4,23,67,3,66,69,13]print('排序前:nums1', nums3)print('排序结果:', merge_sort(nums3))print('排序后:nums1', nums3)# 排序前:nums1 [1, 4, 23, 67, 3, 66, 69, 13]# 排序结果: [1, 3, 4, 13, 23, 66, 67, 69]# 排序后:nums1 [1, 4, 23, 67, 3, 66, 69, 13]
Python内置的sorted使用的是???—> TimSort(多核版的归并排序)
转载地址:http://skbvn.baihongyu.com/