leetcode

Insert Delete GetRandom O(1)

Insert Delete GetRandom O(1)

dict+list Version - 80 ms

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
import random
class RandomizedSet(object):
    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.data = []
        self.idxs = {}
        self.cnt = 0
    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 in self.idxs:
            return False
        else:
            self.data.append(val)
            self.idxs[val] = self.cnt
            self.cnt += 1
            return True
    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.idxs:
            idx, value = self.idxs[val], self.data[-1]
            self.idxs[value], self.data[idx] = idx, value
            self.data.pop()
            self.idxs.pop(val, 0)
            self.cnt -= 1
            return True
        else:
            return False
    def getRandom(self):
        """
        Get a random element from the set.
        :rtype: int
        """
        return random.choice(self.data)
# Your RandomizedSet object will be instantiated and called as such:
# obj = RandomizedSet()
# param_1 = obj.insert(val)
# param_2 = obj.remove(val)
# param_3 = obj.getRandom()

leet code