// Draw a random number in range 0 .. number from command line
// Repeatedly draw new random number to "guess" the first number.
// On each guess remove part of the range
//
// gtowell. Oct 2023
use std::{env, cmp::Ordering};
use rand::Rng;

fn main() {
    let args: Vec<String> = env::args().collect();
    let max_val:u32 = args[1].trim().parse().unwrap();
    let val = rand::thread_rng().gen_range(1..=max_val); // thread_rng init a random num generator -- NOT shared between threads.
    
    let mut lo = 1;
    let mut hi = max_val;
    for z in 0..=((max_val as f64).powf(1.0/4.0) as i32) {  // ..= goes to value inclusive, ..goes to value exclusive ... why the fourth root?? Why not!
        let gg = rand::thread_rng().gen_range(lo..=hi);
        print!("{} ", z);
        match gg.cmp(&val) {
            Ordering::Less => {
                print!("{gg} is too small");
                lo=gg+1;
            },
            Ordering::Greater => {
                print!("{gg} is too big");
                hi=gg-1;
            },
            Ordering::Equal => {
                println!("{gg} is just right");
                return;
            }
        }
        println!("     range {lo}--{hi}");
    }
    
}