#354007 (Rust) No.813 ユキちゃんの冒険

• 問題: No.813 ユキちゃんの冒険
• ユーザー: koba-e964
• 提出日時: 2019-06-26 02:36:49
• 言語: Rust (1.83.0 + proconio)
• 結果: AC
• 実行時間: 1 ms / 2,000 ms
• コード長: 2,279 bytes
• コンパイル時間: 13,249 ms
• コンパイル使用メモリ: 383,944 KB
• 実行使用メモリ: 6,944 KB
• 最終ジャッジ日時: 2024-09-21 08:33:03
• 合計ジャッジ時間: 13,305 ms
• ジャッジサーバーID （参考情報）: judge2 / judge3

ファイルパターン	結果
other	AC * 26

ソースコード

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#[allow(unused_imports)]
use std::cmp::*;
#[allow(unused_imports)]
use std::collections::*;
use std::io::{Write, BufWriter};
// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_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),* )) => {
        ( $(read_value!($next, $t)),* )
    };
    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };
    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };
    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };
    ($next:expr, [ $t:tt ]) => {{
        let len = read_value!($next, usize);
        (0..len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    }};
    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}
fn solve() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($($format:tt)*) => (write!(out,$($format)*).unwrap());
    }
    input! {
        n: usize,
        p: f64,
        q: f64,
    }
    let mut e = vec![0.0; n + 1];
    e[0] = 0.0;
    for i in 1..n + 1 {
        e[i] = p;
        if 1.0 - p * e[i - 1] > 1.0e-9 {
            e[i] += q * q * e[i - 1] / (1.0 - p * e[i - 1]);
        }
    }
    puts!("{}\n", e[n]);
}
fn main() {
    // In order to avoid potential stack overflow, spawn a new thread.
    let stack_size = 104_857_600; // 100 MB
    let thd = std::thread::Builder::new().stack_size(stack_size);
    thd.spawn(|| solve()).unwrap().join().unwrap();
}
 
 
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