結果

問題 No.778 クリスマスツリー
ユーザー cympfh
提出日時 2018-12-27 15:01:45
言語 Rust
(1.83.0 + proconio)
結果
AC  
実行時間 74 ms / 2,000 ms
コード長 2,744 bytes
コンパイル時間 14,585 ms
コンパイル使用メモリ 384,140 KB
実行使用メモリ 25,612 KB
最終ジャッジ日時 2024-10-14 01:53:52
合計ジャッジ時間 14,285 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
(要ログイン)
ファイルパターン 結果
sample AC * 3
other AC * 12
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

#![allow(unused_imports)]
use std::io::{ self, Write };
use std::str::FromStr;
use std::cmp::{ min, max };
use std::collections::{ BinaryHeap, VecDeque };
#[allow(unused_macros)]
macro_rules! trace {
($var:expr) => {
let _ = writeln!(&mut std::io::stderr(), ">>> {} = {:?}", stringify!($var), $var);
};
($($args:expr),*) => { trace!(($($args),*)) }
}
#[allow(unused_macros)]
macro_rules! put {
($var:expr) => {
let _ = writeln!(&mut std::io::stdout(), "{}", $var);
};
($var:expr, $($args:expr),*) => {
let _ = write!(&mut std::io::stdout(), "{} ", $var);
put!($($args),*);
};
}
use std::ops::Range;
struct BIT { size: usize, array: Vec<i32> }
#[allow(dead_code)]
impl BIT {
fn new(n: usize) -> BIT {
BIT { size: n, array: vec![0; n + 1] }
}
fn add(&mut self, idx: usize, w: i32) {
let mut x = idx + 1;
while x <= self.size {
self.array[x] += w;
let xi = x as i32;
x += (xi&-xi) as usize;
}
}
fn sum_up(&self, idx: usize) -> i32 { // [0, idx)
let mut sum = 0;
let mut x = idx;
while x > 0 {
sum += self.array[x];
let xi = x as i32;
x -= (xi&-xi) as usize;
}
sum
}
fn sum(&self, range: Range<usize>) -> i32 {
self.sum_up(range.end) - self.sum_up(range.start)
}
}
fn main() {
let mut sc = Scanner::new();
let n: usize = sc.cin();
let mut bit = BIT::new(n);
let mut tree = vec![vec![]; n];
for i in 1..n {
let a: usize = sc.cin();
tree[a].push(i);
}
let mut stack = vec![(true, 0)];
let mut ans = 0u64;
while let Some((dir, u)) = stack.pop() {
if dir {
ans += bit.sum_up(u) as u64;
bit.add(u, 1);
stack.push((false, u));
for &v in tree[u].iter() {
stack.push((true, v));
}
} else {
bit.add(u, -1);
}
}
put!(ans);
}
#[allow(dead_code)]
struct Scanner { stdin: io::Stdin, buffer: VecDeque<String>, }
#[allow(dead_code)]
impl Scanner {
fn new() -> Scanner { Scanner { stdin: io::stdin(), buffer: VecDeque::new() } }
fn reserve(&mut self) {
while self.buffer.len() == 0 {
let mut line = String::new();
let _ = self.stdin.read_line(&mut line);
for w in line.split_whitespace() {
self.buffer.push_back(String::from(w));
}
}
}
fn cin<T: FromStr>(&mut self) -> T {
self.reserve();
match self.buffer.pop_front().unwrap().parse::<T>() {
Ok(a) => a,
Err(_) => panic!("parse err")
}
}
}
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