mod front_of_house {
    mod hosting {
        fn add_to_waitlist(){}
        fn seat_at_table(){}
    }

    mod serving {
        fn take_order(){}
        fn serve_order(){}
        fn take_payment(){}
    }
}

mod front_of_house {
    pub mod hosting {
        pub fn add_to_waitlist() {}
    }
}
pub fn eat_at_restaurant() {
    // 绝对路径调用方法
    //crate::front_of_house::hosting:add_to_waitlist();
    // 相对路径调用方法
    front_of_house::hosting::add_to_waitlist();
}

fn  serve_order(){}

mod back_of_house {
    fn fix_wrong_order() {
        cook_order();
        // 相对路径调用
        super::serve_order();
        // 绝对路径调用
        crate::serve_order();
    }
    fn cook_order(){}
}

mod front_of_house {
    pub mod hosting {
        pub fn add_to_waitlist(){}

    }
}

pub use crate::front_of_house::hosting;

pub fn eat_at_restaurant() {
    hosting::add_to_waitlist();
    hosting::add_to_waitlist();
}

use rand::Rng;
use std::collections::HashMap;

//use std::collections::HashMap;
//use std::cmp::Ordering;
use std::{cmp::Ordering,io}; // 上面两行缩成一行