結果
問題 | No.778 クリスマスツリー |
ユーザー |
|
提出日時 | 2021-12-10 11:58:57 |
言語 | Rust (1.83.0 + proconio) |
結果 |
AC
|
実行時間 | 79 ms / 2,000 ms |
コード長 | 2,951 bytes |
コンパイル時間 | 22,786 ms |
コンパイル使用メモリ | 384,856 KB |
実行使用メモリ | 34,816 KB |
最終ジャッジ日時 | 2024-07-18 05:48:43 |
合計ジャッジ時間 | 15,738 ms |
ジャッジサーバーID (参考情報) |
judge1 / judge2 |
(要ログイン)
ファイルパターン | 結果 |
---|---|
sample | AC * 3 |
other | AC * 12 |
ソースコード
// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8macro_rules! input {($($r:tt)*) => {let stdin = std::io::stdin();let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));let mut next = move || -> String{bytes.by_ref().map(|r|r.unwrap() as char).skip_while(|c|c.is_whitespace()).take_while(|c|!c.is_whitespace()).collect()};input_inner!{next, $($r)*}};}macro_rules! input_inner {($next:expr) => {};($next:expr,) => {};($next:expr, $var:ident : $t:tt $($r:tt)*) => {let $var = read_value!($next, $t);input_inner!{$next $($r)*}};}macro_rules! read_value {($next:expr, [ $t:tt ; $len:expr ]) => {(0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()};($next:expr, $t:ty) => ($next().parse::<$t>().expect("Parse error"));}/// Binary Indexed Tree (Fenwick Tree). Holds an array of type T./// T is a commutative monoid. Indices are 1 .. n./// Verified by yukicoder No.404 (http://yukicoder.me/submissions/155373)struct BIT<T> {n: usize,ary: Vec<T>,e: T,}impl<T: Clone + std::ops::AddAssign<T>> BIT<T> {fn new(n: usize, e: T) -> Self {let n = n.next_power_of_two();BIT { n: n, ary: vec![e.clone(); n + 1], e: e }}/*** gets the sum in [1 .. idx]* @param idx* @return sum*/fn accum(&self, mut idx: usize) -> T {let mut sum = self.e.clone();while idx > 0 {sum += self.ary[idx].clone();idx &= idx - 1;}sum}/*** performs data[idx] += val;*/fn add<U: Clone>(&mut self, mut idx: usize, val: U)where T: std::ops::AddAssign<U> {assert!(idx > 0);let n = self.n;while idx <= n {self.ary[idx] += val.clone();idx += idx & idx.wrapping_neg();}}}trait Change { fn chmax(&mut self, x: Self); fn chmin(&mut self, x: Self); }impl<T: PartialOrd> Change for T {fn chmax(&mut self, x: T) { if *self < x { *self = x; } }fn chmin(&mut self, x: T) { if *self > x { *self = x; } }}fn main() {// In order to avoid potential stack overflow, spawn a new thread.let stack_size = 104_857_600; // 100 MBlet thd = std::thread::Builder::new().stack_size(stack_size);thd.spawn(|| solve()).unwrap().join().unwrap();}fn dfs(v: usize, ch: &[Vec<usize>], bit: &mut BIT<i64>) -> i64 {let mut ans = bit.accum(v);bit.add(v + 1, 1);for &w in &ch[v] {ans += dfs(w, ch, bit);}bit.add(v + 1, -1);ans}fn solve() {input! {n: usize,a: [usize; n - 1],}let mut ch = vec![vec![]; n];for i in 0..n - 1 {ch[a[i]].push(i + 1);}let mut bit = BIT::new(n, 0);println!("{}", dfs(0, &ch, &mut bit));}