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Penney's game: Difference between revisions
Add Rust implementation
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Heads Heads Tails Heads Tails Heads Tails Tails Tails Tails Tails Tails Tails Heads Heads
You win!
</pre>
=={{header|Rust}}==
<lang rust>
extern crate rand;
use std::io::{stdin, stdout, Write};
use std::thread;
use std::time::Duration;
use rand::Rng;
fn toss_coin<R: Rng>(rng: &mut R, print: bool) -> char {
let c = if rng.gen() { 'H' } else { 'T' };
if print {
print!("{}", c);
stdout().flush().expect("Could not flush stdout");
}
c
}
fn gen_sequence<R: Rng>(rng: &mut R, seed: Option<&str>) -> String {
let mut seq = String::new();
match seed {
Some(s) => {
let mut iter = s.chars();
let c0 = iter.next().unwrap();
let next = if c0 == 'H' { 'T' } else { 'H' };
seq.push(next);
seq.push(c0);
seq.push(iter.next().unwrap());
}
None => {
for _ in 0..3 {
seq.push(toss_coin(rng, false))
}
}
}
seq
}
fn read_sequence(used_seq: Option<&str>) -> String {
let mut seq = String::new();
loop {
seq.clear();
println!("Please, enter sequence of 3 coins: H (heads) or T (tails): ");
stdin().read_line(&mut seq).expect("failed to read line");
seq = seq.trim().to_uppercase();
// do the cheapest test first
if seq.len() == 3
&& seq.chars().all(|c| c == 'H' || c == 'T')
&& seq != used_seq.unwrap_or("")
{
return seq;
}
println!("Please enter correct sequence!");
}
}
fn main() {
let mut rng = rand::thread_rng();
println!("--Penney's game--");
loop {
let useq: String;
let aiseq: String;
if rng.gen::<bool>() {
println!("You choose first!");
useq = read_sequence(None);
println!("Your sequence: {}", useq);
aiseq = gen_sequence(&mut rng, Some(&useq));
println!("My sequence: {}", aiseq);
} else {
println!("I choose first!");
aiseq = gen_sequence(&mut rng, None);
println!("My sequence: {}", aiseq);
useq = read_sequence(Some(&aiseq));
println!("Your sequence: {}", useq);
}
println!("Tossing coins...");
let mut coins = String::new();
for _ in 0..2 {
// toss first 2 coins
coins.push(toss_coin(&mut rng, true));
thread::sleep(Duration::from_millis(500));
}
loop {
coins.push(toss_coin(&mut rng, true));
thread::sleep(Duration::from_millis(500));
if coins.contains(&useq) {
println!("\nYou win!");
break;
}
if coins.contains(&aiseq) {
println!("\nI win!");
break;
}
}
println!(" Play again? 'Y' to play, 'Q' to exit.");
let mut input = String::new();
stdin().read_line(&mut input).expect("failed to read line");
match input.trim_start().chars().next().unwrap() {
'Y' | 'y' => continue,
_ => break,
}
}
}
</lang>
{{out}}
<pre>
--Penney's game--
You choose first!
Please, enter sequence of 3 coins: H (heads) or T (tails):
hht
Your sequence: HHT
My sequence: THH
Tossing coins...
TTTTHTTHTHTHTTTHH
I win!
Play again? 'Y' to play, 'Q' to exit.
</pre>
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