python二分法查找-python之二分法查找

二分法查找主要的作用就是查找元素

规则. 掐头结尾取中间, 必须是有序列

# 二分法查找 (需要你明白和掌握)

# lst = [1,3,5,7,12,36,68,79]

# n = int(input("请输入一个数"))

#

# left = 0

# right = len(lst) - 1

#

# while left <= right:

# mid = (left + right)//2

# if n > lst[mid]:

# left = mid + 1

# elif n < lst[mid]:

# right = mid - 1

# else:

# print("存在")

# break

#

# else:

# print("不存在")

# 递归二 (需要你明白和掌握)

# def func(n, lst, left, right): # 递归找到什么是可以变的. 什么是不可以变的

# if left <= right:

# mid = (left + right) // 2

# if n > lst[mid]:

# left = mid + 1

# return func(n, lst, left, right)

# elif n < lst[mid]:

# right = mid - 1

# return func(n, lst, left, right) # 递归如果有返回值. 所有调用递归的地方必须写return

# else:

# print("找到了")

# return mid # 难点

# else:

# print("找不到")

# return -1

#

# n = int(input("请输入你要查找的数:"))

# lst = [1,3,55,98,37,41,2,5,1,4]

# ret = func(n, lst, 0, len(lst)-1) # 78

# print(ret)

# 最快的查找

lst = [1,3,55,98,37,41,2,5,1,4]

new_lst = []

for i in range(99):

new_lst.append(0)

for i in lst: # 1,3,55,98

new_lst[i] = 1

print(new_lst)

i = int(input("请输入你要找的数据"))

if new_lst[i] == 0: # 1次

print("不存在")

else:

print("存在")