python基础-set函数与sort方法

已知两个list：

a = [9,1,3,5,7]

b = [1,3,4,6,8]

题目一：去重合并排序

思路：set函数取并集
答案一
a = [9,1,3,5,7]
b = [1,3,4,6,8]
c = list(set(a+b))
print(c)
结果
[1, 3, 4, 5, 6, 7, 8, 9]

答案二
a = [9,1,3,5,7]
b = [1,3,4,6,8]
c = list(set(a) | set(b))
print(c)
结果
[1, 3, 4, 5, 6, 7, 8, 9]

题目二：合并取重复的数

思路：set函数取交集
a = [9,1,3,5,7]
b = [1,3,4,6,8]
c = list(set(a) & set(b))
print(c)
结果
[1, 3]

题目三：去掉两个list里相同的数，合并后降序排列

思路：set函数取差集，调sort方法排序
a = [9,1,3,5,7]
b = [1,3,4,6,8]
c = list(set(a) - set(b))
c.sort(reverse=True)
print(c)
结果
[9, 7, 5]

题目四：去掉两个list里相同的数，合并后升序排列

思路：set函数取差集，调sort方法排序
a = [9,1,3,5,7]
b = [1,3,4,6,8]
c = list(set(a) - set(b))
c.sort()
print(c)
结果
[5, 7, 9]