LeetCode/rs/insert-delete-getrandom-o1.rs

use rand::prelude::IteratorRandom;
use std::collections::HashSet;

struct RandomizedSet {
    nums: HashSet<i32>,
}

impl RandomizedSet {
    fn new() -> Self {
        Self {
            nums: HashSet::new(),
        }
    }

    fn insert(&mut self, val: i32) -> bool {
        self.nums.insert(val)
    }

    fn remove(&mut self, val: i32) -> bool {
        self.nums.remove(&val)
    }

    fn get_random(&self) -> i32 {
        let mut rng = rand::thread_rng();
        *self
            .nums
            .iter()
            .choose(&mut rng)
            .expect("at least one number is in the set")
    }
}

/*
 * Your RandomizedSet object will be instantiated and called as such:
 * let obj = RandomizedSet::new();
 * let ret_1: bool = obj.insert(val);
 * let ret_2: bool = obj.remove(val);
 * let ret_3: i32 = obj.get_random();
 */