combinations.rs

#![feature(test)]

extern crate test;
extern crate itertools;

use test::{black_box, Bencher};
use itertools::Itertools;

// approximate 100_000 iterations for each combination
const N1: usize = 100_000;
const N2: usize = 448;
const N3: usize = 86;
const N4: usize = 41;
const N14: usize = 21;

#[bench]
fn combs_for01(b: &mut Bencher) {
    b.iter(|| {
        for i in 0..N1 {
            black_box(vec![i]);
        }
    });
}

#[bench]
fn combs_for02(b: &mut Bencher) {
    b.iter(|| {
        for i in 0..N2 {
            for j in (i + 1)..N2 {
                black_box(vec![i, j]);
            }
        }
    });
}

#[bench]
fn combs_for03(b: &mut Bencher) {
    b.iter(|| {
        for i in 0..N3 {
            for j in (i + 1)..N3 {
                for k in (j + 1)..N3 {
                    black_box(vec![i, j, k]);
                }
            }
        }
    });
}

#[bench]
fn combs_for04(b: &mut Bencher) {
    b.iter(|| {
        for i in 0..N4 {
            for j in (i + 1)..N4 {
                for k in (j + 1)..N4 {
                    for l in (k + 1)..N4 {
                        black_box(vec![i, j, k, l]);
                    }
                }
            }
        }
    });
}

#[bench]
fn combs_c01(b: &mut Bencher) {
    b.iter(|| {
        for combo in (0..N1).combinations(1) {
            black_box(combo);
        }
    });
}

#[bench]
fn combs_c02(b: &mut Bencher) {
    b.iter(|| {
        for combo in (0..N2).combinations(2) {
            black_box(combo);
        }
    });
}

#[bench]
fn combs_c03(b: &mut Bencher) {
    b.iter(|| {
        for combo in (0..N3).combinations(3) {
            black_box(combo);
        }
    });
}

#[bench]
fn combs_c04(b: &mut Bencher) {
    b.iter(|| {
        for combo in (0..N4).combinations(4) {
            black_box(combo);
        }
    });
}

#[bench]
fn combs_c14(b: &mut Bencher) {
    b.iter(|| {
        for combo in (0..N14).combinations(14) {
            black_box(combo);
        }
    });
}