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use std::fmt;
use std::hash::Hash;
pub type DefaultIx = u32;
pub unsafe trait IndexType: Copy + Default + Hash + Ord + fmt::Debug + 'static {
fn new(x: usize) -> Self;
fn index(&self) -> usize;
fn max() -> Self;
}
unsafe impl IndexType for usize {
#[inline(always)]
fn new(x: usize) -> Self {
x
}
#[inline(always)]
fn index(&self) -> Self {
*self
}
#[inline(always)]
fn max() -> Self {
::std::usize::MAX
}
}
unsafe impl IndexType for u32 {
#[inline(always)]
fn new(x: usize) -> Self {
x as u32
}
#[inline(always)]
fn index(&self) -> usize {
*self as usize
}
#[inline(always)]
fn max() -> Self {
::std::u32::MAX
}
}
unsafe impl IndexType for u16 {
#[inline(always)]
fn new(x: usize) -> Self {
x as u16
}
#[inline(always)]
fn index(&self) -> usize {
*self as usize
}
#[inline(always)]
fn max() -> Self {
::std::u16::MAX
}
}
unsafe impl IndexType for u8 {
#[inline(always)]
fn new(x: usize) -> Self {
x as u8
}
#[inline(always)]
fn index(&self) -> usize {
*self as usize
}
#[inline(always)]
fn max() -> Self {
::std::u8::MAX
}
}
use std::cmp::Ordering;
#[derive(Debug, Clone)]
pub struct UnionFind<K> {
parent: Vec<K>,
rank: Vec<u8>,
}
#[inline]
unsafe fn get_unchecked<K>(xs: &[K], index: usize) -> &K {
debug_assert!(index < xs.len());
xs.get_unchecked(index)
}
#[inline]
unsafe fn get_unchecked_mut<K>(xs: &mut [K], index: usize) -> &mut K {
debug_assert!(index < xs.len());
xs.get_unchecked_mut(index)
}
impl<K> UnionFind<K>
where
K: IndexType,
{
pub fn new(n: usize) -> Self {
let rank = vec![0; n];
let parent = (0..n).map(K::new).collect::<Vec<K>>();
UnionFind { parent, rank }
}
pub fn find(&self, x: K) -> K {
assert!(x.index() < self.parent.len());
unsafe {
let mut x = x;
loop {
let xparent = *get_unchecked(&self.parent, x.index());
if xparent == x {
break;
}
x = xparent;
}
x
}
}
pub fn find_mut(&mut self, x: K) -> K {
assert!(x.index() < self.parent.len());
unsafe { self.find_mut_recursive(x) }
}
unsafe fn find_mut_recursive(&mut self, mut x: K) -> K {
let mut parent = *get_unchecked(&self.parent, x.index());
while parent != x {
let grandparent = *get_unchecked(&self.parent, parent.index());
*get_unchecked_mut(&mut self.parent, x.index()) = grandparent;
x = parent;
parent = grandparent;
}
x
}
pub fn equiv(&self, x: K, y: K) -> bool {
self.find(x) == self.find(y)
}
pub fn union(&mut self, x: K, y: K) -> bool {
if x == y {
return false;
}
let xrep = self.find_mut(x);
let yrep = self.find_mut(y);
if xrep == yrep {
return false;
}
let xrepu = xrep.index();
let yrepu = yrep.index();
let xrank = self.rank[xrepu];
let yrank = self.rank[yrepu];
match xrank.cmp(&yrank) {
Ordering::Less => self.parent[xrepu] = yrep,
Ordering::Greater => self.parent[yrepu] = xrep,
Ordering::Equal => {
self.parent[yrepu] = xrep;
self.rank[xrepu] += 1;
}
}
true
}
pub fn into_labeling(mut self) -> Vec<K> {
unsafe {
for ix in 0..self.parent.len() {
let k = *get_unchecked(&self.parent, ix);
let xrep = self.find_mut_recursive(k);
*self.parent.get_unchecked_mut(ix) = xrep;
}
}
self.parent
}
}