leetcode-mid-design-380. Insert Delete GetRandom O(1)

mycode

import random
class RandomizedSet(object):

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

    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.s:

            return False
        else:
            self.s.append(val)
            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.s:
            self.s.remove(val)
            return True
        else:
            return False

    def getRandom(self):
        """
        Get a random element from the set.
        :rtype: int
        """
        return self.s[random.randint(0,len(self.s)-1)]

# 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()

参考：

emmmm。。。我直接调用的？？？我的天。。。

思路:用dic来查找，找到后去insert和删除

import random

class RandomizedSet(object):

    def __init__(self):
        self.data = []
        self.pos = {}

    def insert(self, val):
        if val in self.pos:
            return False

        self.data.append(val)
        self.pos[val] = len(self.data) - 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 not in self.pos:
            return False

        last = self.data[-1]
        elt = self.pos[val]
        self.data[elt] = last
        self.pos[last] = elt
        self.data.pop()
        del self.pos[val]

        return True

    def getRandom(self):
        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()