Leetcode - random set, longest multiclass subsequence

380. O(1) Time insertion 、 Delete and get random elements

Reference resources ：380. O(1) Time insertion 、 Delete and get random elements

Random dictionary ：

• Access data O(1), Using arrays + Dictionaries
• Insertion time , Directly manipulating arrays is O(1) Time
• deleted , Need to reorganize array , You need to save the position at the end of the dictionary , Replace the deleted number , It's also O(1) Time
• Random time , Call directly random.choice(list)

import random

class RandomizedSet:
    """  Random dictionary   Access data O(1), Using arrays  +  Dictionaries   Insertion time , Directly manipulating arrays is O(1) Time ;  deleted , Need to reorganize array , You need to save the position at the end of the dictionary , Replace the deleted number , It's also O(1) Time   Random , Call directly random.choice(list) """
    def __init__