The Computer Language
Benchmarks Game

binary-trees Rust #5 program

source code

// The Computer Language Benchmarks Game
// http://benchmarksgame.alioth.debian.org/
//
// contributed by the Rust Project Developers
// contributed by TeXitoi
// contributed by Cristi Cobzarenco
// contributed by Matt Brubeck
// modified by Tom Kaitchuck
// modified by Volodymyr M. Lisivka
// modified by Ryohei Machida

extern crate bumpalo;
extern crate rayon;

use bumpalo::Bump;
use rayon::prelude::*;

#[derive(Debug, PartialEq, Clone, Copy)]
struct Tree<'a> {
    left: Option<&'a Tree<'a>>,
    right: Option<&'a Tree<'a>>,
}

fn item_check(tree: &Tree) -> i32 {
    if let (Some(left), Some(right)) = (tree.left, tree.right) {
        1 + item_check(right) + item_check(left)
    } else {
        1
    }
}

fn bottom_up_tree<'r>(arena: &'r Bump, depth: i32) -> &'r Tree<'r> {
    let tree = arena.alloc(Tree { left: None, right: None });
    if depth > 0 {
        tree.right = Some(bottom_up_tree(arena, depth - 1));
        tree.left = Some(bottom_up_tree(arena, depth - 1));
    }
    tree
}

fn inner(depth: i32, iterations: i32) -> String {
    let chk: i32 = (0..iterations)
        .into_par_iter()
        .map(|_| {
            let arena = Bump::new();
            let a = bottom_up_tree(&arena, depth);
            item_check(a)
        })
        .sum();
    format!("{}\t trees of depth {}\t check: {}", iterations, depth, chk)
}

fn main() {
    let n = std::env::args().nth(1).and_then(|n| n.parse().ok()).unwrap_or(10);
    let min_depth = 4;
    let max_depth = if min_depth + 2 > n { min_depth + 2 } else { n };

    {
        let arena = Bump::new();
        let depth = max_depth + 1;
        let tree = bottom_up_tree(&arena, depth);
        println!(
            "stretch tree of depth {}\t check: {}",
            depth,
            item_check(tree)
        );
    }

    let long_lived_arena = Bump::new();
    let long_lived_tree = bottom_up_tree(&long_lived_arena, max_depth);

    let messages = (min_depth / 2..=max_depth / 2)
        .into_par_iter()
        .map(|half_depth| {
            let depth = half_depth * 2;
            let iterations = 1 << ((max_depth - depth + min_depth) as u32);
            let res = inner(depth, iterations);
            res
        })
        .collect::<Vec<_>>();

    for message in messages {
        println!("{}", message);
    }

    println!(
        "long lived tree of depth {}\t check: {}",
        max_depth,
        item_check(long_lived_tree)
    );
}
    

notes, command-line, and program output

NOTES:
64-bit Ubuntu quad core
rustc 1.53.0 (53cb7b09b 2021-06-17)
LLVM version: 12.0.1


Wed, 23 Jun 2021 19:08:03 GMT

MAKE:
/opt/src/rust-1.53.0/bin/rustc -C opt-level=3 -C target-cpu=ivybridge --C codegen-units=1 -L /opt/src/rust-libs binarytrees.rs -o binarytrees.rust-5.rust_run

10.36s to complete and log all make actions

COMMAND LINE:
./binarytrees.rust-5.rust_run 21

PROGRAM OUTPUT:
stretch tree of depth 22	 check: 8388607
2097152	 trees of depth 4	 check: 65011712
524288	 trees of depth 6	 check: 66584576
131072	 trees of depth 8	 check: 66977792
32768	 trees of depth 10	 check: 67076096
8192	 trees of depth 12	 check: 67100672
2048	 trees of depth 14	 check: 67106816
512	 trees of depth 16	 check: 67108352
128	 trees of depth 18	 check: 67108736
32	 trees of depth 20	 check: 67108832
long lived tree of depth 21	 check: 4194303