extern crate rand;

use rand::prelude::*;
use std::collections::HashMap;
use std::string::String;

fn main() {
    let mut classes = HashMap::new();
    classes.insert(0, String::from("30C")); //班级1
    classes.insert(1, String::from("37G")); //班级2

    let none_class = String::from("00"); //班级默认值

    let mut rng = thread_rng(); //班级随机器
    let n: u32 = rng.gen_range(0, 2);
    let class = classes.get(&n).unwrap_or(&none_class);

    let mut rng2 = thread_rng(); //学号随机器
    let m: u32 = rng2.gen_range(1, 32); //左边为从1到31号中随机出一位，这是左闭右开区间

    println!("{} {}", class, m); //输出
}