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use std::fmt;
use std::ops::Deref;
use std::slice;
#[derive(Clone)]
pub struct SparseSet {
dense: Vec<usize>,
sparse: Box<[usize]>,
}
impl SparseSet {
pub fn new(size: usize) -> SparseSet {
SparseSet {
dense: Vec::with_capacity(size),
sparse: vec![0; size].into_boxed_slice(),
}
}
pub fn len(&self) -> usize {
self.dense.len()
}
pub fn is_empty(&self) -> bool {
self.dense.is_empty()
}
pub fn capacity(&self) -> usize {
self.dense.capacity()
}
pub fn insert(&mut self, value: usize) {
let i = self.len();
assert!(i < self.capacity());
self.dense.push(value);
self.sparse[value] = i;
}
pub fn contains(&self, value: usize) -> bool {
let i = self.sparse[value];
self.dense.get(i) == Some(&value)
}
pub fn clear(&mut self) {
self.dense.clear();
}
}
impl fmt::Debug for SparseSet {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "SparseSet({:?})", self.dense)
}
}
impl Deref for SparseSet {
type Target = [usize];
fn deref(&self) -> &Self::Target {
&self.dense
}
}
impl<'a> IntoIterator for &'a SparseSet {
type Item = &'a usize;
type IntoIter = slice::Iter<'a, usize>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}