addressable heap has a bug in in_heap() ...

[przygienda]

fn pop(&mut self) -> Option<(Self::Handle, Cost)> {
    if self.binary_tree.is_empty() {
        return None;
    }

    if self.binary_tree.len() > 1 {
        let element = self.binary_tree.swap_remove(0);
        self.update_handle(0);
        self.heap_down(0);
        self.handle_to_index[element.handle as usize] = usize::max_value();
        Some((element.handle, element.cost))
    } else {
        let element = self.binary_tree[0];
        self.binary_tree.clear();
        self.handle_to_index[element.handle as usize] = usize::max_value();
        Some((element.handle, element.cost))
    }
}

#[test]
fn in_heap() {
    let mut h: AddressableBinaryHeap<u64> = AddressableBinaryHeap::new(10);
    h.push(0,1);
    assert!(h.in_heap(0));
    h.push(1,2);
    assert!(h.in_heap(1));
    h.pop();
    h.pop();
    assert!(!h.in_heap(0));
    assert!(!h.in_heap(1));
    h.push(0,1);
    assert!(h.in_heap(0));
}

[przygienda]

in fact checking on something like

const INVALID : usize = usize::max_value();

would be much cleaner ...