Big O 时间复杂度

List
index [ ] O(1)
index assignment O(1)
append O(1)
pop() O(1)
pop(i) O(n)
insert(i, item) O(n)
del operator O(n)
iteration O(n) 扫一遍
contains(in) O(n)
get slice [x:y] O(n) O (k)
del slice O(n)
set slice O(n+k) 把一段赋值
reverse O(n)
concatenate O(k) 后面接了一段
sort O(n log n)
multiply O(nk)

Dictionaries
copy O(n)
get item O(1)
set item O(1) 加一对 (key, value)
delete item O(1)
contain(in) O(1)
iteration O(n)