Python排序部分

codes/python/chapter_sorting/bubble_sort.py

@@ -8,3 +8,30 @@ import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
 from include import *
 
+"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):
+        # 内循环：冒泡操作
+        for j in range(i):
+            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 bubbleSortWithFlag(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):
+        flag=False              #初始化标志位
+        # 内循环：冒泡操作
+        for j in range(i):
+            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
+if __name__=='__main__':
+    nums=[4,1,3,1,5,2]
+    bubble_sort(nums)
+    print("冒泡排序后数组 nums = " ,nums)
+    bubbleSortWithFlag(nums)
+    print("冒泡排序后数组 nums = " ,nums)

codes/python/chapter_sorting/insertion_sort.py

@@ -8,3 +8,19 @@ import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
 from include import *
 
+"直接插入排序"
+def insertionSort(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
+        #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
+            j-=1
+        nums[j+1]=base          #2. 将 base 赋值到正确位置
+
+if __name__=='__main__':
+    nums=[4,1,3,1,5,2]
+    insertionSort(nums)
+    print("排序后数组 nums = " ,nums)

codes/python/chapter_sorting/merge_sort.py

@@ -8,3 +8,41 @@ import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
 from include import *
 
+
+"""
+另一种 思路实现归并排序
+"""
+def merge_sort(nums,l,r):
+    if l>=r:return 
+    mid=l+r>>1                  #划分中点
+    #进行归并
+    merge_sort(nums,l,mid)
+    merge_sort(nums,mid+1,r)
+
+    k,i,j=0,l,mid+1             #借助辅助数组 完成排序
+    while i<=mid and j<=r:  
+        if nums[i]<=nums[j]:    #这一步保证了 稳定排序
+            help_ls[k]=nums[i]
+            i+=1
+        else:
+            help_ls[k]=nums[j]
+            j+=1
+        k+=1
+    
+    while i<=mid:               #对于左边区域
+        help_ls[k]=nums[i]
+        k,i=k+1,i+1
+    while j<=r:                 #对于右边区域
+        help_ls[k]=nums[j]
+        k,j=k+1,j+1
+
+    i,j=l,0
+    while i<=r:
+        nums[i]=help_ls[j]
+        i,j=i+1,j+1
+if __name__=='__main__':
+    nums=[4,1,3,1,5,2]
+    n=len(nums)
+    help_ls=[0 for _ in range(n)]
+    merge_sort(nums,0,n-1)
+    print("归并排序完成后 nums = ",nums)

codes/python/chapter_sorting/quick_sort.py

@@ -8,3 +8,24 @@ import sys, os.path as osp
 sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
 from include import *
 
+
+"另一种思维 实现快速排序"
+def quick_sort(nums,l,r):
+    if l>=r:
+        return 
+    i,j,x=l-1,r+1,nums[l+r>>1]
+    while i<j:
+        while True:
+            i+=1
+            if nums[i]>=x:break
+        while True:
+            j-=1
+            if nums[j]<=x:break
+        if i<j:nums[i],nums[j]=nums[j],nums[i]
+    quick_sort(nums,l,j),quick_sort(nums,j+1,r)
+if __name__=='__main__':
+    nums=[4,1,3,1,5,2]
+    n=len(nums)
+    help_ls=[0 for _ in range(n)]
+    quick_sort(nums,0,n-1)
+    print("快速排序完成后 nums = ",nums)