結果

問題 No.2977 Kth Xor Pair
ユーザー ikdikd
提出日時 2024-12-02 19:11:04
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 560 ms / 3,000 ms
コード長 3,071 bytes
コンパイル時間 12,256 ms
コンパイル使用メモリ 381,136 KB
実行使用メモリ 97,044 KB
最終ジャッジ日時 2024-12-02 19:11:30
合計ジャッジ時間 23,922 ms
ジャッジサーバーID
(参考情報)
judge5 / judge4
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 2
other AC * 34
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ソースコード

diff #
プレゼンテーションモードにする

use proconio::input;
fn main() {
input! {
n: usize,
k: usize,
a: [u32; n],
};
let mut trie = BinaryTrie::new();
for i in 0..n {
trie.add(a[i]);
}
let ans = trie.query(k * 2 + n - 1);
println!("{}", ans);
}
#[derive(Debug, Clone)]
struct Node {
size: usize,
children: [Option<Box<Node>>; 2],
}
impl Node {
fn new() -> Self {
Self {
size: 0,
children: [None, None],
}
}
}
#[derive(Debug)]
struct BinaryTrie {
root: Node,
}
impl BinaryTrie {
fn new() -> Self {
Self { root: Node::new() }
}
fn add(&mut self, value: u32) {
let mut node = &mut self.root;
node.size += 1;
for i in (0..u32::BITS).rev() {
let index = (value >> i & 1) as usize;
node = node.children[index].get_or_insert_with(|| Box::new(Node::new()));
node.size += 1;
}
}
fn list(&self) -> Vec<(u32, usize)> {
fn f(node: &Node, k: Option<u32>, x: u32, acc: &mut Vec<(u32, usize)>) {
match k {
None => {
acc.push((x, node.size));
}
Some(k) => {
let new_k = k.checked_sub(1);
if let Some(zero) = &node.children[0] {
f(zero, new_k, x, acc);
}
if let Some(one) = &node.children[1] {
f(one, new_k, x ^ (1 << k), acc);
}
}
}
}
let mut result = Vec::new();
f(&self.root, Some(u32::BITS - 1), 0, &mut result);
result
}
// ● xor ▲ k (0-indexed)
fn query(&self, k: usize) -> u32 {
let mut nodes = Vec::new();
for (x, l) in self.list() {
nodes.push((&self.root, (x, l)));
}
let (mut count, mut result) = (0, 0);
for i in (0..u32::BITS).rev() {
// result i 0 result
let c = nodes
.iter()
.map(|(n, (x, l))| {
let index = (x >> i & 1) as usize;
match &n.children[index] {
None => 0,
Some(child) => child.size * l,
}
})
.sum::<usize>();
let accept = count + c <= k;
if accept {
result ^= 1 << i;
count += c;
}
nodes.retain_mut(|(n, (x, _))| {
let index = if accept {
(*x >> i & 1) ^ 1
} else {
*x >> i & 1
};
if let Some(ch) = &n.children[index as usize] {
*n = ch;
true
} else {
false
}
});
}
result
}
}
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