还是用的list来解决。
import random class RandomizedCollection(object): def __init__(self): """ Initialize your data structure here. """ self.list1 = [] def insert(self, val): """ Inserts a value to the collection. Returns true if the collection did not already contain the specified element. :type val: int :rtype: bool """ if val in self.list1: self.list1.append(val) return False else: self.list1.append(val) return True def remove(self, val): """ Removes a value from the collection. Returns true if the collection contained the specified element. :type val: int :rtype: bool """ if val in self.list1: self.list1.remove(val) return True else: return False def getRandom(self): """ Get a random element from the collection. :rtype: int """ return random.choice(self.list1)不过看到了题目写的是O(1)，感觉很多都是O(n)啊，不过不知道怎么才能O(1),倒是也给过了
