From 818fb54efb14b9e8580a4fd5ca427be09ffe3161 Mon Sep 17 00:00:00 2001 From: NIngCoder Date: Sat, 26 Nov 2022 00:46:30 +0800 Subject: [PATCH] sort --- codes/python/chapter_sorting/bubble_sort.py | 13 ++--- .../python/chapter_sorting/insertion_sort.py | 7 +-- codes/python/chapter_sorting/merge_sort.py | 17 +++--- codes/python/chapter_sorting/quick_sort.py | 53 +++++++++---------- 4 files changed, 45 insertions(+), 45 deletions(-) diff --git a/codes/python/chapter_sorting/bubble_sort.py b/codes/python/chapter_sorting/bubble_sort.py index 61f11f5..8bbee89 100644 --- a/codes/python/chapter_sorting/bubble_sort.py +++ b/codes/python/chapter_sorting/bubble_sort.py @@ -7,31 +7,32 @@ Author: timi (xisunyy@163.com) from include import * import sys import os.path as osp + sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) """冒泡排序""" def bubble_sort(nums): n = len(nums) # 外循环：待排序元素数量为 n-1, n-2, ..., 1 - for i in range(n-1, -1, -1): + for i in range(n - 1, -1, -1): # 内循环：冒泡操作 for j in range(i): # 交换 nums[j] 与 nums[j + 1] - if nums[j] > nums[j+1]: - nums[j], nums[j+1] = nums[j+1], nums[j] + if nums[j] > nums[j + 1]: + nums[j], nums[j + 1] = nums[j + 1], nums[j] """冒泡排序（标志优化）""" def bubble_sort_with_flag(nums): n = len(nums) # 外循环：待排序元素数量为 n-1, n-2, ..., 1 - for i in range(n-1, -1, -1): + for i in range(n - 1, -1, -1): flag = False # 初始化标志位 # 内循环：冒泡操作 for j in range(i): # 交换 nums[j] 与 nums[j + 1] - if nums[j] > nums[j+1]: - nums[j], nums[j+1] = nums[j+1], nums[j] + if nums[j] > nums[j + 1]: + nums[j], nums[j + 1] = nums[j + 1], nums[j] flag = True # 记录交换元素 if not flag: break # 此轮冒泡未交换任何元素，直接跳出 diff --git a/codes/python/chapter_sorting/insertion_sort.py b/codes/python/chapter_sorting/insertion_sort.py index a3b2b23..0a46af1 100644 --- a/codes/python/chapter_sorting/insertion_sort.py +++ b/codes/python/chapter_sorting/insertion_sort.py @@ -7,6 +7,7 @@ Author: timi (xisunyy@163.com) from include import * import sys import os.path as osp + sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) """插入排序""" @@ -14,12 +15,12 @@ def insertion_sort(nums): # 外循环：base = nums[1], nums[2], ..., nums[n-1] for i in range(1, len(nums)): base = nums[i] - j = i-1 + j = i - 1 # 内循环：将 base 插入到左边的正确位置 while j >= 0 and nums[j] > base: - nums[j+1] = nums[j] # 1. 将 nums[j] 向右移动一位 + nums[j + 1] = nums[j] # 1. 将 nums[j] 向右移动一位 j -= 1 - nums[j+1] = base # 2. 将 base 赋值到正确位置 + nums[j + 1] = base # 2. 将 base 赋值到正确位置 if __name__ == '__main__': diff --git a/codes/python/chapter_sorting/merge_sort.py b/codes/python/chapter_sorting/merge_sort.py index f3212ef..98a2c5f 100644 --- a/codes/python/chapter_sorting/merge_sort.py +++ b/codes/python/chapter_sorting/merge_sort.py @@ -4,12 +4,11 @@ Created Time: 2022-11-25 Author: timi (xisunyy@163.com) ''' -import copy from include import * import sys import os.path as osp -sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) +sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) """ 合并左子数组和右子数组 @@ -18,15 +17,15 @@ sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) """ def merge(nums, left, mid, right): # 初始化辅助数组 借助 copy模块 - tmp = copy.deepcopy(nums[left:right+1]) + tmp = nums[left:right + 1] # 左子数组的起始索引和结束索引 - leftStart, leftEnd = left-left, mid - left + leftStart, leftEnd = left - left, mid - left # 右子数组的起始索引和结束索引 rightStart, rightEnd = mid + 1 - left, right - left # i, j 分别指向左子数组、右子数组的首元素 i, j = leftStart, rightStart # 通过覆盖原数组 nums 来合并左子数组和右子数组 - for k in range(left, right+1): + for k in range(left, right + 1): # 若 “左子数组已全部合并完”，则选取右子数组元素，并且 j++ if i > leftEnd: nums[k] = tmp[j] @@ -45,16 +44,16 @@ def merge(nums, left, mid, right): def merge_sort(nums, left, right): # 终止条件 if left >= right: - return # 当子数组长度为 1 时终止递归 + return # 当子数组长度为 1 时终止递归 # 划分阶段 mid = left + right >> 1 # 计算中点 - merge_sort(nums, left, mid) # 递归左子数组 - merge_sort(nums, mid + 1, right) # 递归右子数组 + merge_sort(nums, left, mid) # 递归左子数组 + merge_sort(nums, mid + 1, right) # 递归右子数组 # 合并阶段 merge(nums, left, mid, right) if __name__ == '__main__': nums = [4, 1, 3, 1, 5, 2] - merge_sort(nums, 0, len(nums)-1) + merge_sort(nums, 0, len(nums) - 1) print("归并排序完成后 nums = ", nums) diff --git a/codes/python/chapter_sorting/quick_sort.py b/codes/python/chapter_sorting/quick_sort.py index 50236e4..658d6a5 100644 --- a/codes/python/chapter_sorting/quick_sort.py +++ b/codes/python/chapter_sorting/quick_sort.py @@ -7,21 +7,20 @@ Author: timi (xisunyy@163.com) from include import * import sys import os.path as osp -sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) +sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) """快速排序类""" class quick_sort(object): - """哨兵划分""" def partition(self, nums, left, right): # 以 nums[left] 作为基准数 i, j = left, right while i < j: while i < j and nums[j] >= nums[left]: - j -= 1 # 从右向左找首个小于基准数的元素 + j -= 1 # 从右向左找首个小于基准数的元素 while i < j and nums[i] <= nums[left]: - i += 1 # 从左向右找首个大于基准数的元素 + i += 1 # 从左向右找首个大于基准数的元素 # 元素交换 nums[i], nums[j] = nums[j], nums[i] # 将基准数交换至两子数组的分界线 @@ -36,14 +35,14 @@ class quick_sort(object): # 哨兵划分 pivot = self.partition(nums, left, right) # 递归左子数组、右子数组 - self.quick_sort(nums, left, pivot-1) - self.quick_sort(nums, pivot+1, right) + self.quick_sort(nums, left, pivot - 1) + self.quick_sort(nums, pivot + 1, right) """快速排序类（中位基准数优化）""" class quick_sort_median(): - # 选取三个元素的中位数 + """选取三个元素的中位数""" def median_three(self, nums, left, mid, right): # 使用了异或操作来简化代码 # 异或规则为 0 ^ 0 = 1 ^ 1 = 0, 0 ^ 1 = 1 ^ 0 = 1 @@ -56,45 +55,44 @@ class quick_sort_median(): """哨兵划分（三数取中值）""" def partition(self, nums, left, right): # 以 nums[left] 作为基准数 - med = self.median_three(nums, left, (left+right)//2, right) + med = self.median_three(nums, left, (left + right) // 2, right) # 将中位数交换至数组最左端 nums[left], nums[med] = nums[med], nums[left] # 以 nums[left] 作为基准数 i, j = left, right while i < j: while i < j and nums[j] >= nums[left]: - j -= 1 # 从右向左找首个小于基准数的元素 + j -= 1 # 从右向左找首个小于基准数的元素 while i < j and nums[i] <= nums[left]: - i += 1 # 从左向右找首个大于基准数的元素 + i += 1 # 从左向右找首个大于基准数的元素 # 元素交换 - nums[i], nums[j] = nums[j], nums[i] - # 将基准数交换至两子数组的分界线 + nums[i], nums[j] = nums[j], nums[i] + # 将基准数交换至两子数组的分界线 nums[i], nums[left] = nums[left], nums[i] - return i # 返回基准数的索引 + return i # 返回基准数的索引 """快速排序""" def quick_sort(self, nums, left, right): # 子数组长度为 1 时终止递归 - if left >= right:return + if left >= right: return # 哨兵划分 pivot = self.partition(nums, left, right) # 递归左子数组、右子数组 - self.quick_sort(nums, left, pivot-1) - self.quick_sort(nums, pivot+1, right) + self.quick_sort(nums, left, pivot - 1) + self.quick_sort(nums, pivot + 1, right) """快速排序类（尾递归优化）""" class quick_sort_tail_call(): - """哨兵划分""" def partition(self, nums, left, right): # 以 nums[left] 作为基准数 i, j = left, right while i < j: while i < j and nums[j] >= nums[left]: - j -= 1 # 从右向左找首个小于基准数的元素 + j -= 1 # 从右向左找首个小于基准数的元素 while i < j and nums[i] <= nums[left]: - i += 1 # 从左向右找首个大于基准数的元素 + i += 1 # 从左向右找首个大于基准数的元素 # 元素交换 nums[i], nums[j] = nums[j], nums[i] # 将基准数交换至两子数组的分界线 @@ -108,25 +106,26 @@ class quick_sort_tail_call(): # 哨兵划分操作 pivot = self.partition(nums, left, right) # 对两个子数组中较短的那个执行快排 - if pivot-left < right-pivot: - self.quick_sort(nums, left, pivot-1) # 递归排序左子数组 - left = pivot+1 # 剩余待排序区间为 [pivot + 1, right] + if pivot - left < right - pivot: + self.quick_sort(nums, left, pivot - 1) # 递归排序左子数组 + left = pivot + 1 # 剩余待排序区间为 [pivot + 1, right] else: - self.quick_sort(nums, pivot+1, right) # 递归排序右子数组 - right = pivot-1 # 剩余待排序区间为 [left, pivot - 1] + self.quick_sort(nums, pivot + 1, right) # 递归排序右子数组 + right = pivot - 1 # 剩余待排序区间为 [left, pivot - 1] + if __name__ == '__main__': # 快速排序 nums = [4, 1, 3, 1, 5, 2] - quick_sort().quick_sort(nums, 0, len(nums)-1) + quick_sort().quick_sort(nums, 0, len(nums) - 1) print("快速排序完成后 nums = ", nums) # 快速排序（中位基准数优化） nums1 = [4, 1, 3, 1, 5, 2] - quick_sort_median().quick_sort(nums1, 0, len(nums1)-1) + quick_sort_median().quick_sort(nums1, 0, len(nums1) - 1) print("快速排序（中位基准数优化）完成后 nums = ", nums) # 快速排序（尾递归优化） nums2 = [4, 1, 3, 1, 5, 2] - quick_sort_tail_call().quick_sort(nums, 0, len(nums2)-1) + quick_sort_tail_call().quick_sort(nums, 0, len(nums2) - 1) print("快速排序（尾递归优化）完成后 nums = ", nums)