#774277 (Rust) No.560 ふしぎなナップサック

• 問題: No.560 ふしぎなナップサック
• ユーザー: elderica
• 提出日時: 2022-06-28 20:33:11
• 言語: Rust (1.77.0)
• 結果: AC
• 実行時間: 1 ms / 2,000 ms
• コード長: 15,325 bytes
• コンパイル時間: 15,425 ms
• コンパイル使用メモリ: 379,172 KB
• 実行使用メモリ: 5,376 KB
• 最終ジャッジ日時: 2024-05-01 10:43:25
• 合計ジャッジ時間: 13,039 ms
• ジャッジサーバーID （参考情報）: judge2 / judge4

入力	結果	実行時間; 実行使用メモリ
testcase_00	AC	1 ms; 5,248 KB
testcase_01	AC	1 ms; 5,376 KB
testcase_02	AC	0 ms; 5,376 KB
testcase_03	AC	1 ms; 5,376 KB
testcase_04	AC	1 ms; 5,376 KB
testcase_05	AC	1 ms; 5,376 KB
testcase_06	AC	0 ms; 5,376 KB
testcase_07	AC	0 ms; 5,376 KB
testcase_08	AC	1 ms; 5,376 KB
testcase_09	AC	1 ms; 5,376 KB
testcase_10	AC	1 ms; 5,376 KB
testcase_11	AC	0 ms; 5,376 KB
testcase_12	AC	1 ms; 5,376 KB
testcase_13	AC	1 ms; 5,376 KB
testcase_14	AC	1 ms; 5,376 KB

ソースコード

use fast_input::FastInput;
use std::io::{stdout, BufWriter, Result, Write};

fn main() -> Result<()> {
    let out = stdout();
    let mut out = BufWriter::new(out.lock());

    let a = Problem::input().solve();
    writeln!(out, "{:?}", a)?;

    Ok(())
}

struct Problem {
    m: usize,
    n: usize,
}

impl Problem {
    fn input() -> Self {
        let input = FastInput::new();
        let (m, n) = input.next_tuple();

        Self { m, n }
    }

    fn solve(&self) -> f64 {
        let mut m = self.m as f64;
        for _ in 0..self.n {
            m = (m * 2.0) + (m + 1.0);
            m /= 3.0;
        }
        m
    }
}

// fast_input
// Klas af Geijerstam <[e-mail]>
// Jakub Jagiello <[e-mail]>
// Licensed under MIT
// https://github.com/KlasafGeijerstam/fast_input/blob/master/src/lib.rs
mod fast_input {
    use std::cell::Cell;
    use std::fmt::Display;
    use std::io::prelude::*;
    use std::io::stdin;
    use std::ops::Deref;
    use std::str::{from_utf8_unchecked, FromStr};

    // #[cfg(test)]
    // mod tests;

    /// Simplifies reading and parsing of known input in a speedy fashion.
    ///
    /// Reads all data on standard in into a byte buffer. Provides
    /// methods to simplify reading and parsing of lines, specifically
    /// aimed to aid in competetive programming where the input is
    /// known and correct. Most functions panic if the input is not correct
    /// and on the specified format. **Note: FastInput assumes *nix line-endings (`\n`)**.
    ///
    /// FastInput uses interior mutability to allow for zero-copy reading and referencing
    /// of string input.
    ///
    /// # Examples
    ///
    /// Creating a new `FastInput` and reading two lines:
    ///
    /// ```no_run
    /// // Input:
    /// // Hello!
    /// // 12 2000
    /// use fast_input::FastInput;
    ///
    /// let input = FastInput::new();
    /// // Must make into String as next_line returns a slice to the internal buffer
    /// // and the second input line advances the internal buffer.
    /// let first_line = input.next_line().to_owned();
    /// let (a, b): (u32, u32) = input.next_tuple();
    ///
    /// println!("First line was: {}, a + b = {}", first_line, a + b);
    /// ```
    ///
    /// Mixing `&str` with parseables:
    ///
    /// To facilitate simple, zero-copy reading of string slices, FastInput
    /// defines the `Str` type. The following example reads (name, age) (&str, u8) pairs
    /// and stores them in a HashMap.
    /// ```no_run
    /// use fast_input::{FastInput, Str};
    /// use std::collections::HashMap;
    ///
    /// // Input:
    /// // Sven 12
    /// // Lorna 22
    /// let input = FastInput::new();
    /// let mut map = HashMap::new();
    /// let (sven, sven_age) = input.next_tuple::<Str, u8>();
    /// let (lorna, lorna_age) = input.next_tuple::<Str, u8>();
    ///
    /// // Deref the Str to a &str
    /// map.insert(*sven, sven_age);
    /// map.insert(*lorna, lorna_age);
    /// assert_eq!(map["Sven"], 12);
    /// ```
    pub struct FastInput {
        data: Vec<u8>,
        pos: Cell<usize>,
    }

    const BUFFER_SIZE: usize = 8196;

    #[allow(dead_code)]
    impl FastInput {
        /// Creates a new FastInput.
        ///
        /// Upon creation the entire contents of standard input will be read.
        /// The function will block until EOF is reached. If you are using a
        /// terminal you can send EOF using `CTRL + D`. The initial buffer size
        /// is 8196 bytes.
        pub fn new() -> Self {
            FastInput {
                data: FastInput::read_to_end(stdin().lock(), BUFFER_SIZE),
                pos: Cell::new(0),
            }
        }

        /// Creates a new FastInput with a specified buffer size.
        ///
        /// For more information, see [`new`].
        pub fn with_buffer_size(buffer_size: usize) -> Self {
            FastInput {
                data: FastInput::read_to_end(stdin().lock(), buffer_size),
                pos: Cell::new(0),
            }
        }

        /// Creates a new FastInput with a given input that implements
        /// Read
        ///
        /// # Examples
        ///
        /// Creating a FastInput over a byte slice:
        /// ```
        /// use fast_input::FastInput;
        /// use std::io::Read;
        ///
        /// let data = "1 2\n3 4".as_bytes();
        ///
        /// let input = FastInput::with_reader(data);
        ///
        /// let (one, two) = input.next_tuple::<u32, u32>();
        /// let (three, four) = input.next_tuple::<u32, u32>();
        ///
        /// assert_eq!((1, 2), (one, two));
        /// assert_eq!((3, 4), (three, four));
        /// assert_eq!(false, input.has_next_line());
        /// ```
        /// For more information, see [`new`].
        pub fn with_reader<T: Read>(input: T) -> Self {
            FastInput {
                data: FastInput::read_to_end(input, BUFFER_SIZE),
                pos: Cell::new(0),
            }
        }

        /// Reads the next line and returns it.
        ///
        /// # Panics
        ///
        /// The function panics if there is no more data in the buffer.
        /// If you are unsure if there is a next line, see [`has_next_line`].
        pub fn next_line(&self) -> &str {
            if let Some(nline) = self.next_newline() {
                unsafe {
                    let pos = self.pos.get();
                    let s = from_utf8_unchecked(&self.data[pos..nline]);
                    self.pos.set(nline + 1);
                    s
                }
            } else {
                unsafe {
                    let s = from_utf8_unchecked(&self.data[self.pos.get()..]);
                    self.pos.set(self.data.len());
                    s
                }
            }
        }

        /// Reads a single value and parses it.
        ///
        /// # Examples
        ///
        /// Reading an integer:
        /// ```no_run
        /// //Input:
        /// //123
        /// use fast_input::FastInput;
        ///
        /// let input = FastInput::new();
        /// let number: i32 = input.next();
        /// println!("{}", number);
        /// ```
        pub fn next<'a, T: FastParse<'a>>(&'a self) -> T {
            let mut it = self.next_as_iter();
            it.next().unwrap()
        }

        /// Reads two elements separated by a space, and returns them parsed as a tuple.
        ///
        /// # Examples
        ///
        /// Reading an `i32` and a `f64`:
        /// ```no_run
        /// use fast_input::FastInput;
        ///
        /// let input = FastInput::new();
        /// let (age, length): (i32, f64) = input.next_tuple();
        /// println!("{} {}", age, length);
        /// ```
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        pub fn next_tuple<'a, T1: FastParse<'a>, T2: FastParse<'a>>(&'a self) -> (T1, T2) {
            let mut it = self.next_split();
            (
                T1::fparse(it.next().unwrap()),
                T2::fparse(it.next().unwrap()),
            )
        }

        /// Reads three elements separated by a space, and returns them as a triple.
        ///
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        pub fn next_triple<'a, T1: FastParse<'a>, T2: FastParse<'a>, T3: FastParse<'a>>(
            &'a self,
        ) -> (T1, T2, T3) {
            let mut it = self.next_split();
            (
                T1::fparse(it.next().unwrap()),
                T2::fparse(it.next().unwrap()),
                T3::fparse(it.next().unwrap()),
            )
        }

        /// Reads four elements separated by a space, and returns them as a quad-tuple.
        ///
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        pub fn next_quad<
            'a,
            T1: FastParse<'a>,
            T2: FastParse<'a>,
            T3: FastParse<'a>,
            T4: FastParse<'a>,
        >(
            &'a self,
        ) -> (T1, T2, T3, T4) {
            let mut it = self.next_split();
            (
                T1::fparse(it.next().unwrap()),
                T2::fparse(it.next().unwrap()),
                T3::fparse(it.next().unwrap()),
                T4::fparse(it.next().unwrap()),
            )
        }

        /// Reads five elements separated by a space, and returns them as a quintuple.
        ///
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        pub fn next_quintuple<
            'a,
            T1: FastParse<'a>,
            T2: FastParse<'a>,
            T3: FastParse<'a>,
            T4: FastParse<'a>,
            T5: FastParse<'a>,
        >(
            &'a self,
        ) -> (T1, T2, T3, T4, T5) {
            let mut it = self.next_split();
            (
                T1::fparse(it.next().unwrap()),
                T2::fparse(it.next().unwrap()),
                T3::fparse(it.next().unwrap()),
                T4::fparse(it.next().unwrap()),
                T5::fparse(it.next().unwrap()),
            )
        }

        /// Reads the next line and returns an iterator over the elements of the line.
        ///
        /// # Examples
        ///
        /// Collecting a line into a [`Vec`] of integers.
        /// ```no_run
        /// use fast_input::FastInput;
        ///
        /// let input = FastInput::new();
        /// let numbers: Vec<u32> = input.next_as_iter().collect();
        /// println!("Last line contained {} numbers!", numbers.len());
        /// ```
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        pub fn next_as_iter<'a, T: FastParse<'a>>(&'a self) -> impl Iterator<Item = T> + '_ {
            self.next_line().trim().split(' ').map(|x| T::fparse(x))
        }

        /// Reads the next line and returns an iterator over the elements (no parsing).
        ///
        /// # Examples
        ///
        /// Reading a sentence and printing the individual words:
        /// ```no_run
        /// use fast_input::FastInput;
        ///
        /// let input = FastInput::new();
        /// let words = input.next_split();
        /// for (i, word) in words.enumerate() {
        ///     println!("Word {} was: {}", i, word);
        /// }
        /// ```
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        pub fn next_split<'a>(&'a self) -> impl Iterator<Item = &'a str> + '_ {
            self.next_line().trim().split(' ')
        }

        /// Checks if there is more data available in the buffer.
        ///
        /// # Examples
        ///
        /// Reading until EOF:
        /// ```no_run
        /// use fast_input::FastInput;
        ///
        /// let input = FastInput::new();
        /// while input.has_next_line() {
        ///     println!("{}", input.next_line());
        /// }
        /// ```
        pub fn has_next_line(&self) -> bool {
            self.pos.get() != self.data.len()
        }

        /// Returns the next line as a str tuple.
        ///
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        #[deprecated(
            since = "0.1.1",
            note = "Use `next_tuple` with the `Str` type instead."
        )]
        pub fn next_str_tuple(&self) -> (&str, &str) {
            let mut line = self.next_line().trim().split(' ');
            (line.next().unwrap(), line.next().unwrap())
        }

        /// Returns the next line as a str triple.
        ///
        /// # Panics
        /// If there is no more data in the buffer. See [`has_next_line`].
        #[deprecated(
            since = "0.1.1",
            note = "Use `next_triple` with the `Str` type instead."
        )]
        pub fn next_str_triple(&self) -> (&str, &str, &str) {
            let mut line = self.next_line().trim().split(' ');
            (
                line.next().unwrap(),
                line.next().unwrap(),
                line.next().unwrap(),
            )
        }

        fn read_to_end<T: Read>(mut input: T, buffer_size: usize) -> Vec<u8> {
            let mut data = Vec::with_capacity(buffer_size);
            input.read_to_end(&mut data).unwrap();
            data
        }

        fn next_newline(&self) -> Option<usize> {
            let mut i = self.pos.get();
            while i < self.data.len() && self.data[i] != b'\n' {
                i += 1;
            }
            if i < self.data.len() && self.data[i] == b'\n' {
                Some(i)
            } else {
                None
            }
        }

        /// Returns a (consuming) iterator over all remaining lines.
        ///
        /// # Examples
        ///
        /// Printing all lines:
        /// ```rust
        /// use fast_input::FastInput;
        ///
        /// let data = "First\nSecond\nThird".as_bytes();
        /// let input = FastInput::with_reader(data);
        /// let all_lines: Vec<_> = input.lines().collect();
        ///
        /// assert_eq!(&all_lines, &["First", "Second", "Third"]);
        /// assert_eq!(input.has_next_line(), false);
        /// ```
        ///
        pub fn lines<'a>(&'a self) -> impl Iterator<Item = &str> + 'a {
            (0..)
                .take_while(move |_| self.has_next_line())
                .map(move |_| self.next_line())
        }
    }

    impl Default for FastInput {
        fn default() -> Self {
            Self::new()
        }
    }

    /// Helper trait for parsing.
    /// Mainly used to avoid repeating type constraints.
    pub trait FastParse<'a> {
        /// Parses a type from a string slice
        fn fparse(s: &'a str) -> Self;
    }

    impl<'a, T: FromStr> FastParse<'a> for T
    where
        <T as FromStr>::Err: std::fmt::Debug,
    {
        fn fparse(s: &'a str) -> Self {
            s.parse().unwrap()
        }
    }

    /// Allows reading of string slices (`&str`).
    /// The standard library does not provide a `FromStr` implementation
    /// for `&str`. The `Str` type newtypes `&str` and implements `FastParse`
    /// and `Deref<Target = &str>`.
    ///
    /// # Examples
    ///
    /// Reading (name, age, city) triples using `Str` and `FastInput`:
    /// ```rust
    /// use fast_input::{FastInput, Str};
    /// let data = "Jakub 26 Mora".as_bytes();
    /// let input = FastInput::with_reader(data);
    /// let (name, age, city) = input.next_triple::<Str, u8, Str>();
    /// // Str implements Display
    /// println!("The person is called {}, is {} years old and lives in {}", name, age, city);
    ///
    /// //To use any functions related to `&str`, dereference the `Str` into a `&str`
    /// let name: &str = *name;
    ///
    /// ```
    pub struct Str<'a>(&'a str);

    impl<'a> FastParse<'a> for Str<'a> {
        fn fparse(s: &'a str) -> Self {
            Str::<'a>(s)
        }
    }

    impl<'a> Deref for Str<'a> {
        type Target = &'a str;
        fn deref(&self) -> &Self::Target {
            &self.0
        }
    }

    impl Display for Str<'_> {
        fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            self.0.fmt(fmt)
        }
    }
}