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|
use std::{
cmp::{Ordering, PartialOrd},
collections::HashSet,
};
type Graph = Vec<Vec<usize>>;
fn add_edge(graph: &mut Graph, source: usize, target: usize) {
let len = graph.len();
if source >= len {
panic!("source = {source} >= len = {len}");
}
if target >= len {
panic!("target = {target} >= len = {len}");
}
if !graph.get(source).unwrap().contains(&target) {
graph.get_mut(source).unwrap().push(target);
}
if !graph.get(target).unwrap().contains(&source) {
graph.get_mut(target).unwrap().push(source);
}
}
fn sm1<T: PartialOrd>(a: Vec<T>, count: &mut usize) -> (usize, Graph) {
let n = a.len();
if n == 0 {
panic!("invalid empty input");
}
let mut result: Graph = std::iter::repeat_with(Default::default).take(n).collect();
let mut indices: Vec<usize> = (0..n).collect();
let mut upper_bound = n;
while upper_bound > 1 {
for i in 0..(upper_bound.div_euclid(2)) {
*count += 1;
let x = *indices.get(2 * i).unwrap();
let y = *indices.get(2 * i + 1).unwrap();
add_edge(&mut result, x, y);
match a.get(x).unwrap().partial_cmp(a.get(y).unwrap()) {
Some(Ordering::Less) | Some(Ordering::Equal) => {
*indices.get_mut(i).unwrap() = x;
}
Some(_) => {
*indices.get_mut(i).unwrap() = y;
}
None => {
if a.get(x).unwrap().partial_cmp(a.get(x).unwrap()).is_some() {
*indices.get_mut(i).unwrap() = x;
} else {
*indices.get_mut(i).unwrap() = y;
}
}
}
}
let offset = upper_bound.rem_euclid(2);
if offset == 1 {
*indices.get_mut(upper_bound.div_euclid(2)).unwrap() =
*indices.get(upper_bound - 1).unwrap();
}
upper_bound = upper_bound.div_euclid(2) + offset;
}
(*indices.first().unwrap(), result)
}
fn sm<T: PartialOrd>(a: Vec<T>, count: &mut usize) -> Vec<usize> {
let n = a.len();
let mut result: Vec<usize> = Vec::with_capacity(n);
let mut added: Vec<bool> = std::iter::repeat(false).take(n).collect();
let mut g_to_a_s: Vec<Vec<usize>> = Vec::with_capacity(n);
g_to_a_s.push((0..n).collect());
let mut lis: Vec<Graph> = vec![];
for i in 0..n {
let g: Vec<&T> = g_to_a_s
.last()
.unwrap()
.iter()
.copied()
.map(|x| a.get(x).unwrap())
.collect();
let g_len = g.len();
assert_eq!(Some(g_len), g_to_a_s.last().map(|v| v.len()));
let (hi, li) = sm1(g, count);
assert!(hi < g_len);
let hi = *g_to_a_s.last().unwrap().get(hi).unwrap();
result.push(hi);
if i + 1 == n {
// early break to prevent unnecessary efforts
break;
}
*added.get_mut(hi).unwrap() = true;
lis.push(li);
assert_eq!(lis.len(), i + 1);
assert_eq!(g_to_a_s.len(), i + 1);
let mut new_g_to_a: Vec<usize> = Vec::new();
let mut new_g_to_a_set: HashSet<usize> = Default::default();
for j in 0..=i {
let mut ell_j: Vec<usize> = Vec::new();
let i_j = g_to_a_s.get(j).unwrap();
let index = i_j.iter().position(|x| *x == hi);
if let Some(x_j) = index {
for y in lis.get(j).unwrap().get(x_j).unwrap().iter().copied() {
ell_j.push(*i_j.get(y).unwrap());
}
}
for x in ell_j {
if !new_g_to_a_set.contains(&x) && !added.get(x).unwrap() {
new_g_to_a.push(x);
new_g_to_a_set.insert(x);
}
}
}
g_to_a_s.push(new_g_to_a);
}
result
}
fn main() {
// sample: 1 3 4 0 2 3 5 1
let inputs: Vec<f32> = std::env::args()
.skip(1)
.map(|arg| arg.parse().unwrap())
.collect();
// let enumeration: Vec<f32> = (0..inputs.len()).map(|n| n as f32).collect();
// println!(" {enumeration:?}");
if inputs.is_empty() {
println!("Please input some numbers to sort.");
return;
}
println!("inputs: {inputs:?}");
let mut count = 0;
let sort = sm(inputs.clone(), &mut count);
let sort_result: Vec<f32> = sort
.iter()
.copied()
.map(|n| *inputs.get(n).unwrap())
.collect();
println!("sort indices = {sort:?}\nsort result: {sort_result:?}\ncount = {count}");
}
|
