petgraph 0.8.3

Graph data structure library. Provides graph types and graph algorithms.
Documentation 
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extern crate petgraph;
extern crate rand;

use petgraph::unionfind::UnionFind;
use rand::{thread_rng, ChaChaRng, Rng, SeedableRng};
use std::collections::HashSet;

#[test]
fn uf_test() {
    let n = 8;
    let mut u = UnionFind::new(n);
    for i in 0..n {
        assert_eq!(u.find(i), i);
        assert_eq!(u.find_mut(i), i);
        assert!(!u.union(i, i));
    }

    u.union(0, 1);
    assert_eq!(u.find(0), u.find(1));
    u.union(1, 3);
    u.union(1, 4);
    u.union(4, 7);
    assert_eq!(u.find(0), u.find(3));
    assert_eq!(u.find(1), u.find(3));
    assert!(u.find(0) != u.find(2));
    assert_eq!(u.find(7), u.find(0));
    u.union(5, 6);
    assert_eq!(u.find(6), u.find(5));
    assert!(u.find(6) != u.find(7));

    // check that there are now 3 disjoint sets
    let set = (0..n).map(|i| u.find(i)).collect::<HashSet<_>>();
    assert_eq!(set.len(), 3);
}

#[test]
fn uf_test_checked() {
    let n = 8;
    let mut u = UnionFind::new(n);
    for i in 0..n {
        assert_eq!(u.try_find(i), Some(i));
        assert_eq!(u.try_find_mut(i), Some(i));
        assert_eq!(u.try_union(i, i), Ok(false));
    }

    assert!(u.try_union(0, 1).is_ok());
    assert_eq!(u.try_find(0), u.try_find(1));
    assert!(u.try_find(0).is_some());
    assert!(u.try_union(1, 3).is_ok());
    assert!(u.try_union(1, 4).is_ok());
    assert!(u.try_union(4, 7).is_ok());
    assert_eq!(u.try_find(0), u.try_find(3));
    assert_eq!(u.try_find(1), u.try_find(3));
    assert!(u.try_find(0).is_some());
    assert!(u.try_find(1).is_some());
    assert!(u.try_find(0) != u.try_find(2));
    assert_eq!(u.try_find(7), u.try_find(0));
    assert!(u.try_union(5, 6).is_ok());
    assert_eq!(u.try_find(6), u.try_find(5));
    assert!(u.try_find(6) != u.try_find(7));

    // check that there are now 3 disjoint sets
    let set = (0..n).map(|i| u.find(i)).collect::<HashSet<_>>();
    assert_eq!(set.len(), 3);
}

#[test]
fn uf_test_with_equiv() {
    let n = 8;
    let mut u = UnionFind::new(n);
    for i in 0..n {
        assert_eq!(u.find(i), i);
        assert_eq!(u.find_mut(i), i);
        assert!(u.equiv(i, i));
    }

    u.union(0, 1);
    assert!(u.equiv(0, 1));
    u.union(1, 3);
    u.union(1, 4);
    u.union(4, 7);
    assert!(u.equiv(0, 7));
    assert!(u.equiv(1, 3));
    assert!(!u.equiv(0, 2));
    assert!(u.equiv(7, 0));
    u.union(5, 6);
    assert!(u.equiv(6, 5));
    assert!(!u.equiv(6, 7));

    // check that there are now 3 disjoint sets
    let set = (0..n).map(|i| u.find(i)).collect::<HashSet<_>>();
    assert_eq!(set.len(), 3);
}

#[test]
fn uf_test_with_checked_equiv() {
    let n = 8;
    let mut u = UnionFind::new(n);
    for i in 0..n {
        assert_eq!(u.find(i), i);
        assert_eq!(u.find_mut(i), i);
        assert_eq!(u.try_equiv(i, i), Ok(true));
    }

    u.union(0, 1);
    assert_eq!(u.try_equiv(0, 1), Ok(true));
    u.union(1, 3);
    u.union(1, 4);
    u.union(4, 7);
    assert_eq!(u.try_equiv(0, 7), Ok(true));
    assert_eq!(u.try_equiv(1, 3), Ok(true));
    assert_eq!(u.try_equiv(0, 2), Ok(false));
    assert_eq!(u.try_equiv(7, 0), Ok(true));
    u.union(5, 6);
    assert_eq!(u.try_equiv(6, 5), Ok(true));
    assert_eq!(u.try_equiv(6, 7), Ok(false));

    // check that there are now 3 disjoint sets
    let set = (0..n).map(|i| u.find(i)).collect::<HashSet<_>>();
    assert_eq!(set.len(), 3);
}

#[test]
fn uf_rand() {
    let n = 1 << 14;
    let mut rng = ChaChaRng::from_rng(thread_rng()).unwrap();
    let mut u = UnionFind::new(n);
    for _ in 0..100 {
        let a = rng.gen_range(0, n);
        let b = rng.gen_range(0, n);
        let ar = u.find(a);
        let br = u.find(b);
        assert_eq!(ar != br, u.union(a, b));
    }
}

#[test]
fn uf_u8() {
    let n = 256;
    let mut rng = ChaChaRng::from_rng(thread_rng()).unwrap();
    let mut u = UnionFind::<u8>::new(n);
    for _ in 0..(n * 8) {
        let a = rng.gen();
        let b = rng.gen();
        let ar = u.find(a);
        let br = u.find(b);
        assert_eq!(ar != br, u.union(a, b));
    }
}

#[test]
fn uf_u8_checked() {
    let n = 256;
    let mut rng = ChaChaRng::from_rng(thread_rng()).unwrap();
    let mut u = UnionFind::<u8>::new(n);
    for _ in 0..(n * 8) {
        let a = rng.gen();
        let b = rng.gen();
        let ar = u.try_find(a).unwrap();
        let br = u.try_find(b).unwrap();
        assert_eq!(ar != br, u.try_union(a, b).unwrap());
    }
}

#[test]
fn labeling() {
    let mut u = UnionFind::<u32>::new(48);
    for i in 0..24 {
        u.union(i + 1, i);
    }
    for i in 25..47 {
        u.union(i, i + 1);
    }
    u.union(23, 25);
    u.union(24, 23);
    let v = u.into_labeling();
    assert!(v.iter().all(|x| *x == v[0]));
}

#[test]
fn uf_incremental() {
    let mut u = UnionFind::<u32>::new_empty();
    assert_eq!(u.new_set(), 0);
    assert_eq!(u.new_set(), 1);
    assert_eq!(u.len(), 2);
    u.union(0, 1);
    assert_eq!(u.find(0), u.find(1));
    assert_eq!(u.new_set(), 2);
    assert_eq!(u.new_set(), 3);
    u.union(1, 3);
    assert_eq!(u.new_set(), 4);
    u.union(1, 4);
    assert_eq!(u.new_set(), 5);
    assert_eq!(u.new_set(), 6);
    assert_eq!(u.new_set(), 7);
    assert_eq!(u.len(), 8);
    u.union(4, 7);
    assert_eq!(u.find(0), u.find(3));
    assert_eq!(u.find(1), u.find(3));
    assert!(u.find(0) != u.find(2));
    assert_eq!(u.find(7), u.find(0));
    u.union(5, 6);
    assert_eq!(u.find(6), u.find(5));
    assert!(u.find(6) != u.find(7));

    // check that there are now 3 disjoint sets
    let set = (0..u.len() as u32)
        .map(|i| u.find(i))
        .collect::<HashSet<_>>();
    assert_eq!(set.len(), 3);
}

#[test]
fn uf_test_out_of_bounds() {
    let n = 8;
    let mut u = UnionFind::new(n);
    for i in 0..n {
        u.find(i);
        u.find_mut(i);
        u.union(i, i);
    }

    assert!(u.try_find(50).is_none());
    assert!(u.try_find_mut(50).is_none());

    assert_eq!(u.try_union(1, 50), Err(50));
    assert_eq!(u.try_union(50, 1), Err(50));
    assert_eq!(u.try_union(30, 50), Err(30));
    assert_eq!(u.try_union(50, 30), Err(50));

    assert_eq!(u.try_equiv(1, 50), Err(50));
    assert_eq!(u.try_equiv(50, 1), Err(50));
    assert_eq!(u.try_equiv(30, 50), Err(30));
    assert_eq!(u.try_equiv(50, 30), Err(50));
}