常数时间删除/查找数组中的任意元素

380. 常数时间插入、删除和获取随机元素 https://leetcode.cn/problems/insert-delete-getrandom-o1

380. Insert Delete GetRandom O(1) https://leetcode.com/problems/insert-delete-getrandom-o1

710. 黑名单中的随机数 https://leetcode.cn/problems/random-pick-with-blacklist

710. Random Pick with Blacklist https://leetcode.com/problems/random-pick-with-blacklist

实现随机集合

避开黑名单的随机数