冒泡 选择 二分法 算法 排序算法

#冒泡排序；
# def bubble_sort(alist):
#     n=len(alist)         #计算序列长度
#     for i in range(n-1): #遍历无序序列；
#         for j in range(n-1-i):         #构建循环比较相邻的元素条件；
#             if alist[j]>alist[j+1]:    #如果前一个比后面相邻元素大（升序）；
#                 alist[j],alist[j+1]=alist[j+1],alist[j]     #交换他们两个；
# if __name__ == '__main__':
#     alist=[99,54,78,21,33,11,60]
#     bubble_sort(alist)
#     print(alist)


#选择排序；
# def select_sort(alist):
#     n=len(alist)
#     for i in range(n-1):   #需要进行n-1次操作
#         min_index=i        #记录最小位置
#         for j in range(i+1,n): #从i+1位置到末尾选择出最小数据
#             if alist[min_index]>alist[j]:
#                 min_index=j
#         if min_index!=i:    #如果选择出的位置不再正确位置，进行交换
#             alist[i],alist[min_index]=alist[min_index],alist[i]
# if __name__ == '__main__':
#     alist=[44,33,100,77,88,1,32,89,32]
#     select_sort(alist)
#     print(alist)

# def select_sort(alist):
#     n=len(alist)
#     for i in range(n-1):   #需要进行n-1次操作
#         min_index=i    #记录最小位置
#         for j in range(i+1,n):    #遍历无序列表
#             if alist[min_index]>alist[j]:  #判断当前数值是否小于最小值，如果小于，记录索引
#                 min_index=j        #记录索引
#         if min_index!=i:   #判断min_index索引是否相同，不相同，做数值交换
#             alist[i],alist[min_index]=alist[min_index],alist[i]    #不相同做数值交换
# if __name__ == '__main__':
#     alist=[22,34,11,56,43,99,0]
#     select_sort(alist)
#     print(alist)



#二分法（非递归）
# def binary_search(alist,item):
#     n=len(alist)     #计算序列长度
#     first=0          #构造初始索引
#     last=n-1         #构造结束索引
#     while first<=last:        #构造循环查找条件
#         mid=(first+last)//2   #构造折半查找的中间值
#         if alist[mid]==item:  #如果元素等于中间值的情况
#             return True
#         elif alist[mid]>item:  #如果元素小于中间值的情况
#             last=mid+1
#         else:                  #如果元素大于中间值的情况
#             first=mid-1
#     else:               #如果整个序列中查找一遍都没找到，返回False
#         return False
# if __name__ == '__main__':
#     alist=[11,33,21,43,66,54,777]
#     print(binary_search(alist,66))



#二分法(递归)
# def binary_search(alist,item):
#     if alist==[]:    #判断是否为空列表
#         return False                # 如果为空则返回未找到
#     else:            #否则，构造中间值
#         mid=len(alist)//2
#         if alist[mid]==item:   #如果元素等于中间值的情况
#             return True
#         elif alist[mid]>item:  #如果元素小于中间值的情况
#             return binary_search(alist[:mid],item)
#         else:                 #如果元素大于中间值的情况
#             return binary_search(alist[mid+1:],item)
#
# if __name__ == '__main__':
#     alist = [11, 33, 43, 66, 777]
#     print(binary_search(alist,11))


"""
有无序序列alist=[22,1,3,4,55,66,7,8,9,10]
使用二分法查找元素22
"""
# class Search(object):
#     def bubble_sort(self):
#         n=len(alist)
#         for i in range(n-1):
#             for j in range(n-1-i):
#                 if alist[j]>alist[j+1]:
#                     alist[j],alist[j+1]=alist[j+1],alist[j]
#         print(alist)
#     def binary_search(self,item):
#         n = len(alist)
#         first = 0
#         last = n - 1
#         while first <= last:
#             mid = (first + last) // 2
#             if alist[mid] == item:
#                 return True
#             elif alist[mid] > item:
#                 last = mid - 1
#             else:
#                 first = mid + 1
#         else:
#             return False
#
# if __name__ == '__main__':
#     alist = [22, 1, 3, 4, 55, 66, 7, 8, 9, 10]
#     search=Search()
#     search.bubble_sort()
#     print(search.binary_search(22))


# class Search(object):
#     def __init__(self):
#         self.alist = [5,44,99,8,101,1,22,33]
#     def bubble_sort(self):
#         print(self.alist)
#         n = len(self.alist)
#         for i in range(n-1):
#             for j in range(n-1-i):
#                 if self.alist[j] > self.alist[j+1]:
#                     self.alist[j],self.alist[j+1] = self.alist[j+1],self.alist[j]
#         print(self.alist)
#     def binary_search(self,item):
#         a = 0
#         b = len(self.alist) - 1
#         while a <= b:
#             mid = (a + b) // 2
#             if self.alist[mid] == item:
#                 return True
#             elif self.alist[mid] > item:
#                 b = mid - 1
#             else:
#                 a = mid + 1
#         return False
#
# if __name__ == '__main__':
#     aaa = Search()
#     aaa.bubble_sort()
#     print(aaa.binary_search(44))

# import time
# start_time=time.time
# for a in range(1001):
#     for b in range(1001):
#         for c in range(1001):
#             if a+b+c==1000 and a**2+b**2==c**2:
#                 print("a=%d,b=%d,c=%d"%(a,b,c))
# end_time=time.time()
# print("最终的执行时间为：%f"%(end_time-start_time))


"""
a,b,c三个数
1.a+b+c=1000   (0--1000)
2.a**2+b**2=c**2
求a,b,c可能的组合
"""
# import time
# start_time=time.time()
# for a in range(0,1001):
#     for b in range(0,1001):
#         for c in range(0,1001):
#             if a+b+c == 1000 and a**2+b**2 == c**2:
#                 print(" a = %d , b = %d , c = %d "%(a,b,c))
# end_time=time.time()
# print("demo执行共耗时：%f"%(end_time-start_time))


# import time
# start_time=time.time()
# for a in range(0,1001):
#     for b in range(0,1001):
#         c=1000-a-b
#         if a+b+c == 1000 and a**2+b**2 == c**2:
#             print(" a = %d , b = %d , c = %d "%(a,b,c))
# end_time=time.time()
# print("demo执行共耗时：%f"%(end_time-start_time))


# def func():
#     for a in range(0,1001):
#         for b in range(0,1001):
#             c=1000-a-b
#             if a**2+b**2 == c**2:
#                 print(" a = %d , b = %d , c = %d "%(a,b,c))
# import timeit   #python内置性能测试模块；
#
# time01=timeit.Timer(stmt="func()",setup="from __main__ import func")
#            #Timer(目标函数从哪去找这个函数)
# print(time01.timeit(1))


# import timeit   #查看demo运行时间
# def t1():       #列表拼接；
#     l=[]
#     for i in range(1000):
#         l=l+[i]
#
# def t2():        #append;
#     l=[]
#     for i in range(1000):
#         l.append(i)
#
# def t3():          #列表推导式；
#     l=[i for i in range(1000)]
#
# def t4():         #强制转换；
#     l=list(range(1000))
#
# def t5():          #insert;
#     l=[]
#     for i in range(10000):
#         l.insert(0,i)
#
#
# from timeit import Timer
# timer1=Timer("t1","from __main__ import t1")
# print("列表拼接:",timer1.timeit(number=10000),"seconds")
#
# timer2=Timer("t2()","from __main__ import t2")
# print("append",timer2.timeit(number=10000),"seconds")
#
# timer3=Timer("t3()","from __main__ import t3")
# print("列表推导式",timer3.timeit(number=10000),"seconds")
#
# timer4=Timer("t4()","from __main__ import t4")
# print("list强转",timer4.timeit(number=10000),"seconds")
#
# timer5 = timeit.Timer(stmt='t5()', setup='from __main__ import t5')
# print('insert:',timer5.timeit(1000))




# import timeit   # 查看demo运行时间
# def t1():   # 列表拼接
#     ll = []
#     for i in range(10000):
#         ll += [i]
#
# def t2():   # append
#     ll = []
#     for i in range(10000):
#         ll.append(i)
#
# def t3():   #  列表推导式
#     ll = [i for i in range(10000)]
#
# def t4():   # 强制转换
#     ll = list(range(10000))
#
# def t5():    # insert
#     ll = []
#     for i in range(10000):
#         ll.insert(0,i)
#
# timer1 = timeit.Timer(stmt='t1()', setup='from __main__ import t1')
# timer2 = timeit.Timer(stmt='t2()', setup='from __main__ import t2')
# timer3 = timeit.Timer(stmt='t3()', setup='from __main__ import t3')
# timer4 = timeit.Timer(stmt='t4()', setup='from __main__ import t4')
# timer5 = timeit.Timer(stmt='t5()', setup='from __main__ import t5')
#
# print('列表拼接:',timer1.timeit(1000))
# print('append:',timer2.timeit(1000))
# print('列表推导式:',timer3.timeit(1000))
# print('list强转:',timer4.timeit(1000))
# print('insert:',timer5.timeit(1000))