leetcode之 Insert Delete GetRandom O(1)

import random
class RandomizedSet(object):

def __init__(self):
"""
Initialize your data structure here.
"""
self.list1 = []

def insert(self, val):
"""
Inserts a value to the set. Returns true if the set did not already contain the specified element.
:type val: int
:rtype: bool
"""
if val not in self.list1:
self.list1.append(val)
return True
else:
return False

def remove(self, val):
"""
Removes a value from the set. Returns true if the set 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 set.
:rtype: int
"""
return random.choice(self.list1)