將元素添加到列表中的特定位置

Question

#Say I have the lists 
l1 = [2,3,6,7,9] 
l2 = [11,14,16,20,21] 

# and a random number, say 8 
x = 8 

# And I want to change l1 so that if there is any number larger than 
# 8 it will be deleted, then 8 will be inserted into the end of l1 
# the output would look like this: [2,3,6,7,8] 

# And I want to change l2 so that if there is any number smaller than 
# 8 it will be deleted, then 8 will be inserted into the beginning of l2 
# the output would look like this: [8,11,14,16,20,21] 

我不知道如何去解決這個問題，並真誠感謝您的幫助。謝謝！

Answer 1

使用列表理解：

l1 = [i for i in l1 if i <= 8] 
l1 = l1 + [8] 

（或l1.append(8)）

和：

l2 = [i for i in l2 if i >= 8] 
l2 = [8] + l2 

（或l2.insert(0, 8)這大概是更快）

Answer 2

這裏有一個解決方案：

l1 = [i for i in l1 if i <= x] 

l1.append(x) 

l2 = [i for i in l2 if i >= x] 

l2.insert(0, x)