並列計算 & 多倍長 in Rust

ackermann.rs

// main.rsにコピペする

// Cargo.toml
// [dependencies]
// num-traits = "0.2.7"
// num-bigint = "0.2"


extern crate num_traits;
extern crate num_bigint;

use num_traits::{Zero, One};
use num_bigint::BigUint;
use std::thread;


fn v(x: u8) -> BigUint {
    match x {
        0 => Zero::zero(), //let f0: BigUint = Zero::zero(); f0,
        _ => One ::one(), //let f1: BigUint = One ::one();  f1,
    }
}

fn ack(m: u8, n: BigUint) -> BigUint {
    if m == 0 {
        n + v(1)
    } else if n == v(0) {
        ack(m - 1, v(1))
    } else {
        ack(m - 1, ack(m, n - v(1)))
    }
}

fn main() {
    // スレッド生成器の準備
    let builder = thread::Builder::new();

    // スタックサイズを指定してスレッドを生成する
    let th = builder.stack_size(100000000);

    // 実行  cargo run --release で10分くらい
    let handle = th.spawn(|| {
        println!("ack(4, 2じゃなくて1): {}", ack(4, v(1)));
    }).unwrap();
    let _ = handle.join();
}

mc.rs

// main.rsにコピペする

use std::thread;


fn fib(n: u32) -> u32 {
    match n {
        0 => 0,
        1 => 1,
        _ => fib(n - 2) + fib(n - 1),
    }
}

fn main() {
    let mut handles = vec![];

    for x in 39..43 {
        let handle = thread::spawn(move || {
            println!("Result: {} {}", x, fib(x));
        });
        handles.push(handle);
    }

    for handle in handles {
        handle.join().unwrap();
    }

    println!("hello from main thread!");
}