Proconio

https://docs.rs/proconio
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Easy-to-use I/O library for competitive programming in Rust, providing convenient macros for reading...
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### Examples for #[fastout]

Source: https://docs.rs/proconio-derive/%5E0.2.0

Illustrates the usage of the `fastout` attribute macro to enable buffered stdout, which can significantly improve performance for programs with large amounts of output. The example shows how `print!` and `println!` behave with `fastout` enabled.

```rust
use proconio_derive::fastout;

#[fastout]
fn main() {
    print!("{}{}, ", 'h', "ello"); // "hello"       (no newline) 
    println!("{}!", "world");      // "world!\n"
    println!("{}", 123456789);     // "123456789\n"
}
```

--------------------------------

### input_interactive usage example

Source: https://docs.rs/proconio/latest/proconio/macro.input_interactive.html

Example of how to use the input_interactive macro, showing its similarity to the input! macro with a custom source.

```rust
let source = procontio::source::line::LineSource::new(BufReader::new(std::io::stdin()));
input! {
    from &mut source,
    (mut) variable: type,
    ...
}
```

--------------------------------

### Reading values from a source

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Example demonstrating how to read a specified number of values from a source and sum them up.

```rust
#![allow(unused_imports)]
use proconio::source::AutoSource;
use proconio::read_value;
let mut source = AutoSource::from("2 3 4");
let mut sum = 0;
for _ in 0..read_value!(from &mut source, usize) {
    sum += read_value!(from &mut source, u32);
}
assert_eq!(sum, 7);
```

--------------------------------

### read_value usage examples

Source: https://docs.rs/proconio/latest/proconio/macro.read_value.html

Examples demonstrating how to use the read_value macro to read input.

```rust
let variable = read_value!(type);
let variable = read_value!(with runtime_readable);
// or
let variable = read_value!(from source, type);
let variable = read_value!(from source, with runtime_readable);
```

--------------------------------

### Input Array Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading an array of fixed size and a 2D array using the `input!` macro.

```rust
let source = AutoSource::from("5 3 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5");

input! {
    from source,
    n: usize,
    m: usize,
    a: [i32; n],
    b: [[i32; n]; m] // no trailing comma is OK
}

assert_eq!(a, [1, 2, 3, 4, 5]);
assert_eq!(b, [[1, 2, 3, 4, 5], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5]]);
```

--------------------------------

### Input Tuple Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading tuples of a fixed size using the `read_value!` macro.

```rust
let mut source = AutoSource::from("4 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5");

let n = read_value!(from &mut source, usize);
let t = read_value!(from &mut source, [(i32, i32, i32, i32, i32); n]);

assert_eq!(
    t,
    [
        (1, 2, 3, 4, 5),
        (1, 2, 3, 4, 5),
        (1, 2, 3, 4, 5),
        (1, 2, 3, 4, 5)
    ]
);
```

--------------------------------

### Input Usize1 Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading values as `Usize1` (1-based indexing) using the `input!` macro.

```rust
use crate::marker::Usize1;

let mut source = AutoSource::from("4 1 2 3 4 5 6 7 8");

input! {
    from &mut source,
    n: usize,
}

for i in 0..n {
    input! {
        from &mut source,
        from: Usize1, to: Usize1
    }

    assert_eq!(from, i * 2);
    assert_eq!(to, i * 2 + 1);
}
```

--------------------------------

### Example of #[fastout] usage

Source: https://docs.rs/proconio/%5E0.4.0

Demonstrates how to use the `#[fastout]` attribute on the main function to make `print!` and `println!` faster.

```rust
use proconio::fastout;

#[fastout]
fn main() {
    print!("{}{}, ", 'h', "ello"); // "hello"       (no newline)
    println!("{}!", "world");      // "world!\n"
    println!("{}", 123456789);     // "123456789\n"
}
```

--------------------------------

### Example Usage of VecReadable

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading a vector of `Usize1` values after reading the count `n`.

```rust
let mut source = AutoSource::from("4 1 2 3 4");
let n = read_value!(from &mut source, usize);
let v = read_value!(from &mut source, with VecReadable::<crate::marker::Usize1>::new(n));

assert_eq!(v, [0, 1, 2, 3]);
```

--------------------------------

### Input Mut Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading a mutable variable `n` and then using it in a loop to read other values.

```rust
let mut source = AutoSource::from("8 1 2 3 4 5 6 7 8");

input! {
    from &mut source,
    mut n: usize,
}

let mut sum = 0;
while n > 0 {
    input!(from &mut source, x: u32);
    sum += x;
    n -= 1;
}
assert_eq!(sum, 36);
```

--------------------------------

### LineSource from &str

Source: https://docs.rs/proconio/latest/proconio/source/line/struct.LineSource.html

Example of creating a LineSource from a string slice by wrapping it in BufReader.

```rust
fn from(s: &'a str) -> LineSource<BufReader<&'a [u8]>>
```

--------------------------------

### Example of #[fastout] usage

Source: https://docs.rs/proconio/latest/proconio/index.html

Demonstrates the usage of the #[fastout] attribute on the main function to speed up print! and println! macros.

```rust
use proconio::fastout;

#[fastout]
fn main() {
    print!("{}{}, ", 'h', "ello"); // "hello"       (no newline) 
    println!("{}!", "world");      // "world!\n" 
    println!("{}", 123456789);     // "123456789\n" 
}
```

--------------------------------

### Basic usage of #[fastout] in main

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

This example demonstrates the basic usage of the `#[fastout]` attribute on the `main` function to enable fast output. It includes a spawned thread to show how output might be handled in concurrent scenarios.

```rust
#! 
use proconio::fastout;

# fn some_function(_: String) -> impl Iterator<Item = String> { vec!["hello".to_string(), "world".to_string()].into_iter() }
# fn some_proc(x: &str) -> &str { x }

#[fastout]
fn main() {
    let context = "some context".to_string();
    let thread = std::thread::spawn(move || {
        // Use many println! and the order is very important
        // It's possible to aggregate the result and print it later, but it's not easy to read
        // and seems ugly.
        println!("this is header.");
        for (i, item) in some_function(context).enumerate() {
            print!("Item #{}: ", i);
            print!("{}", some_proc(&item));
            println!("({})", item);
        }
    });

    thread.join().unwrap();
}

```

--------------------------------

### Using AutoSource with input!

Source: https://docs.rs/proconio/latest/proconio/source/index.html

This example demonstrates how to use `AutoSource` to read input from a string literal. It shows how to specify the source to be used in the `input!` macro.

```rust
use proconio::source::auto::AutoSource;
use proconio::input;

let source = AutoSource::from("32 54 -23");
input! {
    from source,
    n: u8,
    m: u32,
    l: i32,
}

println!("{} {} {}", n, m, l);
assert_eq!(n, 32);
assert_eq!(m, 54);
assert_eq!(l, -23);

```

--------------------------------

### Input Variable Length Array (VLA) Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading a variable length array (VLA) using the `input!` macro.

```rust
let source = AutoSource::from("5 3 1 2 3 2 1 2 4 1 2 3 4 0 6 1 2 3 4 5 6");

input! {
    from source,
    n: usize,
    a: [[i32]; n],
}

assert_eq!(
    a,
    vec![
        vec![1, 2, 3],
        vec![1, 2],
        vec![1, 2, 3, 4],
        vec![],
        vec![1, 2, 3, 4, 5, 6],
    ]
);
```

--------------------------------

### RuntimeReadable Trait Example

Source: https://docs.rs/proconio/latest/src/proconio/source/mod.rs.html

An example demonstrating the implementation and usage of the RuntimeReadable trait to read a directed graph where the number of nodes and edges are determined at runtime.

```rust
use proconio::source::RuntimeReadable;
use proconio::source::auto::AutoSource;
use proconio::source::Source;
use proconio::input;
use proconio::marker::Usize1;
use std::io::BufRead;
struct DirectedGraph(usize, usize);
impl RuntimeReadable for DirectedGraph {
    type Output = Vec<Vec<usize>>;

    fn read<R: BufRead, S: Source<R>>(self, source: &mut S) -> Self::Output {
        let DirectedGraph(n, m) = self;

        input! {
            from source,
            edges: [(Usize1, Usize1); m],
        };

        let mut g = vec![vec![]; n];
        for e in edges {
            g[e.0].push(e.1);
        }
        g
    }
}

let mut source = AutoSource::from("2 3\n1 1\n1 2\n2 2\n");
input! {
    from source,
    n: usize,
    m: usize,
    g: with DirectedGraph(n, m),
}

```

--------------------------------

### Input Min as Isize1 Panic Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates that reading `isize::MIN` as `Isize1` causes a panic.

```rust
use crate::marker::Isize1;
let min_string = isize::MIN.to_string();
let mut source = AutoSource::from(&*min_string);
input! {
    from &mut source,
    _v: Isize1,
}
```

--------------------------------

### Read Value Array Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading an array of fixed size and a 2D array using the `read_value!` macro.

```rust
let mut source = AutoSource::from("5 3 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5");

let n = read_value!(from &mut source, usize);
let m = read_value!(from &mut source, usize);
let a = read_value!(from &mut source, [i32; n]);
let b = read_value!(from &mut source, [[i32; n]; m]);

assert_eq!(a, [1, 2, 3, 4, 5]);
assert_eq!(b, [[1, 2, 3, 4, 5], [1, 2, 3, 4, 5], [1, 2, 3, 4, 5]]);
```

--------------------------------

### Input Multiple Times Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates using the `input!` macro multiple times within a loop to read data incrementally.

```rust
let mut source = AutoSource::from("4 1 2 3 4\n1 2\r\n\r\n3 4");

input! {
    from &mut source,
    n: usize,
}

for i in 0..n {
    input! {
        from &mut source,
        j: i32, k: i32,
    }

    assert_eq!(j, if i % 2 == 0 { 1 } else { 3 });
    assert_eq!(k, if i % 2 == 0 { 2 } else { 4 });
}
```

--------------------------------

### Combined Types

Source: https://docs.rs/proconio/%5E0.4.0

Example of combining different types, including arrays of tuples.

```rust
use proconio::input;

input! {
    n: usize,
    m: usize,
    t: [([u32; m], i32); n],
}
```

--------------------------------

### Input Zero as Usize1 Panic Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates that reading a zero value as `Usize1` causes a panic.

```rust
use crate::marker::Usize1;
let mut source = AutoSource::from("0");
input! {
    from &mut source,
    _v: Usize1,
}
```

--------------------------------

### Read Value Variable Length Array (VLA) Example

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates reading a variable length array (VLA) using the `read_value!` macro.

```rust
let mut source = AutoSource::from("5 3 1 2 3 2 1 2 4 1 2 3 4 0 6 1 2 3 4 5 6");

let n = read_value!(from &mut source, usize);
let a = read_value!(from &mut source, [[i32]; n]);

assert_eq!(
    a,
    vec![
        vec![1, 2, 3],
        vec![1, 2],
        vec![1, 2, 3, 4],
        vec![],
        vec![1, 2, 3, 4, 5, 6],
    ]
);
```

--------------------------------

### Using #[fastout] on a separate function

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

This example shows how to apply `#[fastout]` to a separate function (`process`) that is called from `main`. This is a valid use case, but it highlights the potential for deadlocks if `#[fastout]` is also applied to the caller in a multithreaded context.

```rust
# #[cfg(feature = "derive")]
# {
use proconio::fastout;

# fn some_function(_: String) -> impl Iterator<Item = String> { vec!["hello".to_string(), "world".to_string()].into_iter() }
# fn some_proc(x: &str) -> &str { x }

// You can add #[fastout] here
#[fastout]
fn process(context: String) {
    // It's completely OK since this #[fastout] is a thing inside `process()`
    println!("this is header.");
    for (i, item) in some_function(context).enumerate() {
        print!("Item #{}: ", i);
        print!("{}", some_proc(&item));
        println!("({})", item);
    }
}

// You must not add #[fastout] here!  It causes deadlock.
// #[fastout]
fn main() {
    let context = "some context".to_string();
    let thread = std::thread::spawn(move || process(context));
    thread.join().unwrap();
}
# }

```

--------------------------------

### Example of printing order issue with #[fastout]

Source: https://docs.rs/proconio/%5E0.4.0

This code snippet illustrates a potential issue with printing order when using #[fastout] and calling other functions between print statements.

```rust
fn foo() { println!("between"); }
#[fastout]
fn main() {
    println!("hello");
    foo();
    println!("world");
}
```

--------------------------------

### Deriving `Readable` with `#[derive_readable]`

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

An example of using `#[derive_readable]` to make custom structs like `Weight`, `Cost`, and `Edge` readable by the `input!` macro.

```rust
# #[cfg(feature = "derive")]
# {
# extern crate proconio;
use proconio::input;
# use proconio::source::auto::AutoSource;
use proconio::derive_readable;

// Unit struct can derive readable.  This generates a no-op for the reading.  Not ignoring
// the read value, but simply skip reading process.  You cannot use it to discard the input.
#[derive_readable]
#[derive(PartialEq, Debug)]
struct Weight;

#[derive_readable]
#[derive(PartialEq, Debug)]
struct Cost(i32);

#[derive_readable]
#[derive(Debug)]
struct Edge {
    from: usize,
    to: proconio::marker::Usize1, // The real Edge::to has type usize.
    weight: Weight,
    cost: Cost,
}

fn main() {
#   let source = AutoSource::from("12 32 35");
    input! {
#       from source,
        edge: Edge,
    }

    // if you enter "12 32 35" to the stdin, the values are as follows.
    assert_eq!(edge.from, 12);
    assert_eq!(edge.to, 31);
    assert_eq!(edge.weight, Weight);
    assert_eq!(edge.cost, Cost(35));
}
# }

```

--------------------------------

### read_value! macro usage

Source: https://docs.rs/proconio/latest/index.html

Example demonstrating the direct usage of the read_value! macro, typically when the value does not need to be stored in a variable.

```rust
use proconio::source::auto::AutoSource;
use proconio::read_value;
let mut source = AutoSource::from("2 3 4");
let mut sum = 0;
for _ in 0..read_value!(from &mut source, usize) {
    sum += read_value!(from &mut source, u32);
}
assert_eq!(sum, 7);
```

--------------------------------

### Examples for #[derive_readable]

Source: https://docs.rs/proconio-derive/%5E0.2.0

Demonstrates how to use the `derive_readable` attribute macro to automatically implement the `Readable` trait for custom structs, including unit structs, tuple structs, and structs with various field types. It shows how to read complex nested structures from standard input using `proconio::input!`.

```rust
use proconio::input;
use proconio_derive::derive_readable;

// Unit struct can derive readable.  This generates a no-op for the reading.  Not ignoring
// the read value, but simply skip reading process.  You cannot use it to discard the input.
#[derive_readable]
#[derive(PartialEq, Debug)]
struct Weight;

#[derive_readable]
#[derive(PartialEq, Debug)]
struct Cost(i32);

#[derive_readable]
#[derive(Debug)]
struct Edge {
    from: usize,
    to: proconio::marker::Usize1, // The real Edge::to has type usize.
    weight: Weight,
    cost: Cost,
}

fn main() {
    input! {
        edge: Edge,
    }

    // if you enter "12 32 35" to the stdin, the values are as follows.
    assert_eq!(edge.from, 12);
    assert_eq!(edge.to, 31);
    assert_eq!(edge.weight, Weight);
    assert_eq!(edge.cost, Cost(35));
}
```

--------------------------------

### input! macro usage

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates the basic syntax for the `input!` macro, showing how to specify the input source, declare variables (mutable or immutable), and define their types, including support for `RuntimeReadable` types.

```rust
input! {
    from source,
    (mut) variable: type,
    (mut) variable: with runtime_readable,
    ...
}
```

--------------------------------

### From<&str> implementation

Source: https://docs.rs/proconio/latest/proconio/source/once/struct.OnceSource.html

Demonstrates creating a OnceSource from a string slice.

```rust
impl<'a> From<&'a str> for OnceSource<BufReader<&'a [u8]>> {
    fn from(s: &'a str) -> OnceSource<BufReader<&'a [u8]>> {
        // ... implementation details ...
    }
}
```

--------------------------------

### Basic Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

The macro's user interface is basically the same with tanakh's input macro.

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
# let source = AutoSource::from("32 54 -23");

input! {
#   from source,
    n: u8,
    m: u32,
    l: i32,
}

// now you can use n, m and l as variable.
println!("{} {} {}", n, m, l);
# assert_eq!(n, 32);
# assert_eq!(m, 54);
# assert_eq!(l, -23);

```

--------------------------------

### new function

Source: https://docs.rs/proconio/latest/proconio/source/once/struct.OnceSource.html

Creates a new OnceSource using a specified BufRead reader.

```rust
pub fn new(source: R) -> OnceSource<R>
```

--------------------------------

### Search Tricks

Source: https://docs.rs/proconio/latest/help.html

Tips for using the search functionality in Rustdoc, including type prefixes and path searches.

```text
Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given item kind.
Accepted kinds are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.
Search functions by type signature (e.g., `vec -> usize` or `-> vec` or `String, enum:Cow -> bool`)
You can look for items with an exact name by putting double quotes around your request: `"string"`
Look for functions that accept or return slices and arrays by writing square brackets (e.g., `-> [u8]` or `[] -> Option`)
Look for items inside another one by searching for a path: `vec::Vec`
```

--------------------------------

### Keyboard Shortcuts

Source: https://docs.rs/proconio/latest/help.html

A list of keyboard shortcuts available in Rustdoc for navigation and interaction.

```text
`?`
    Show this help dialog

`S` / `/`
    Focus the search field

`↑`
    Move up in search results

`↓`
    Move down in search results

`←` / `→`
    Switch result tab (when results focused)

`⏎`
    Go to active search result

`+` / `=`
    Expand all sections

`-`
    Collapse all sections

`_`
    Collapse all sections, including impl blocks
```

--------------------------------

### DirectedGraph Implementation of RuntimeReadable

Source: https://docs.rs/proconio/latest/proconio/source/trait.RuntimeReadable.html

An example implementation of the RuntimeReadable trait for a DirectedGraph struct, demonstrating how to read graph data whose size is determined at runtime.

```rust
struct DirectedGraph(usize, usize);
impl RuntimeReadable for DirectedGraph {
    type Output = Vec<Vec<usize>>;

    fn read<R: BufRead, S: Source<R>>(self, source: &mut S) -> Self::Output {
        let DirectedGraph(n, m) = self;

        input! {
            from source,
            edges: [(Usize1, Usize1); m],
        };

        let mut g = vec![vec![]; n];
        for e in edges {
            g[e.0].push(e.1);
        }
        g
    }
}
```

--------------------------------

### Basic Input

Source: https://docs.rs/proconio/%5E0.4.0

Demonstrates reading basic integer types (u8, u32, i32) using the input! macro.

```rust
use proconio::input;

input! {
    n: u8,
    m: u32,
    l: i32,
}

// now you can use n, m and l as variable.
println!("{} {} {}", n, m, l);
```

--------------------------------

### input! macro test case: string and byte input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Test case for the input! macro with String, Chars, and Bytes types.

```Rust
#[test]
fn input_str() {
use crate::marker::{Bytes, Chars};
let source = AutoSource::from("  string   chars\nbytes");

input! {
from source,
string: String,
chars: Chars,
bytes: Bytes,
}

assert_eq!(string, "string");
assert_eq!(chars, ['c', 'h', 'a', 'r', 's']);
assert_eq!(bytes, b"bytes");
}
```

--------------------------------

### Resolving `#[fastout]` error with closures

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Example showing how to resolve the compilation error when using closures with `print!` or `println!` inside a `#[fastout]` function by returning the result from the thread.

```rust
# #[cfg(feature = "derive")]
# {
use proconio::fastout;

#[fastout]
fn main() {
    let thread = std::thread::spawn(|| {
        let x = 3;
        x * x
    });

    let y = thread.join().unwrap();
#   assert_eq!(y, 9);
    println!("{}", y);
}
# }
```

--------------------------------

### Reading Strings, Chars, and Bytes

Source: https://docs.rs/proconio/%5E0.4.0

Shows how to read input into a String, Vec<char> (Chars), and Vec<u8> (Bytes).

```rust
use proconio::input;
use proconio::marker::{Bytes, Chars};

input! {
    string: String, // read as String
    chars: Chars,   // read as Vec<char>
    bytes: Bytes,   // read as Vec<u8>
}

// if you enter "string chars bytes" to the stdin, they are like this.
assert_eq!(string, "string");
assert_eq!(chars, ['c', 'h', 'a', 'r', 's']);
assert_eq!(bytes, b"bytes");
```

--------------------------------

### Input Macro Usage with RuntimeReadable

Source: https://docs.rs/proconio/latest/proconio/source/trait.RuntimeReadable.html

An example showing how to use the input! macro with a type that implements RuntimeReadable, like DirectedGraph, to read data whose dimensions are known at runtime.

```rust
input! {
    n: usize,
    m: usize,
    g: with DirectedGraph(n, m),
}
```

--------------------------------

### Tuple Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

You can read tuples:

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
# let source = AutoSource::from("1 2 3 4 5");

input! {
#   from source,
    t: (i32, i32, i32, i32, i32),
}

// if you enter "1 2 3 4 5" to the stdin, `t` is like this.
assert_eq!(t, (1, 2, 3, 4, 5));

```

--------------------------------

### Potential printing order issue with #[fastout]

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

This example illustrates how `#[fastout]` can alter the printing order when other functions are called between print statements. The output might show 'between' before 'hello' and 'world' due to buffering.

```rust
# #[cfg(feature = "derive")]
# {
# use proconio::fastout;
fn foo() { println!("between"); }
#[fastout]
fn main() {
    println!("hello");
    foo();
    println!("world");
}
# }

```

--------------------------------

### Combined Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

And you can freely combine these types.

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
# let source = AutoSource::from("4 3 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5");

input! {
#   from source,
    n: usize,

```

--------------------------------

### Input Error: Different Format

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Test case for `input!` macro panicking when the input format is incorrect (empty).

```rust
let mut source = AutoSource::from("");
input! {
    from &mut source,
    _n: i32,
}
```

--------------------------------

### String, Bytes, and Chars Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Strings can be read as `Vec<u8>` or `Vec<char>`. Use `Bytes` and `Chars` to do so:

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
use proconio::marker::{Bytes, Chars};
# let source = AutoSource::from("  string   chars\nbytes");

input! {
#     from source,
    string: String, // read as String
    chars: Chars,   // read as Vec<char>
    bytes: Bytes,   // read as Vec<u8>
}

// if you enter "string chars bytes" to the stdin, they are like this.
assert_eq!(string, "string");
assert_eq!(chars, ['c', 'h', 'a', 'r', 's']);
assert_eq!(bytes, b"bytes");

```

--------------------------------

### Mutable Variables

Source: https://docs.rs/proconio/%5E0.4.0

Shows how to declare and use mutable variables with the input! macro.

```rust
use proconio::input;

input! {
    n: u32,
    mut m: u32,
}

m += n; // OK: m is mutable
```

--------------------------------

### Multiple Input Calls

Source: https://docs.rs/proconio/%5E0.4.0

Shows how to use the input! macro multiple times to read data across different calls, useful for multiple datasets.

```rust
use proconio::input;

input! {
    n: usize,
}

for i in 0..n {
    input! {
        m: usize,
        a: [i32; m],
    }
}
```

--------------------------------

### OnceSource Implementation

Source: https://docs.rs/proconio/latest/src/proconio/source/once.rs.html

Implementation of OnceSource for reading all input at once.

```Rust
1// Copyright 2019 statiolake <statiolake@gmail.com>
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
5// http://opensource.org/licenses/MIT>, at your option. This file may not be copied, modified, or
6// distributed except according to those terms.
7
8use super::Source;
9use crate::source::tokens::Tokens;
10use std::io::BufRead;
11use std::marker::PhantomData;
12
13/// Source reading entire content for the first time.
14///
15/// It is a wrapper for `BufRead`.  You can create `OnceSource` from any type implementing
16/// `BufRead`.
17pub struct OnceSource<R: BufRead> {
18    tokens: Tokens,
19
20    // to consume `R`.  Actually `OnceSource` is not need to have `R`, since reading is done in its
21    // constructor.  This is for the consistency with `LineSource` (To use smoothly through `AutoSource`).
22    _read: PhantomData<R>,
23}
24
25impl<R: BufRead> OnceSource<R> {
26    /// Creates `Source` using specified reader of `BufRead`.
27    pub fn new(mut source: R) -> OnceSource<R> {
28        let mut context = String::new();
29        source
30            .read_to_string(&mut context)
31            .expect("failed to read from source; maybe an IO error.");
32
33        OnceSource {
34            tokens: context.into(),
35            _read: PhantomData,
36        }
37    }
38}
39
40impl<R: BufRead> Source<R> for OnceSource<R> {
41    /// Gets a next token.
42    fn next_token(&mut self) -> Option<&str> {
43        self.tokens.next_token()
44    }
45
46    /// Check if tokens are empty
47    fn is_empty(&mut self) -> bool {
48        self.tokens.is_empty()
49    }
50}
51
52use std::io::BufReader;
53
54/// You can create `OnceSource` from `&str`.  Since `&[u8]` is a `Read`, `BufRead` can be easily
55/// created by wrapping using `BufReader`.
56impl<'a> From<&'a str> for OnceSource<BufReader<&'a [u8]>> {
57    fn from(s: &'a str) -> OnceSource<BufReader<&'a [u8]>> {
58        OnceSource::new(BufReader::new(s.as_bytes()))
59    }
60}
```

--------------------------------

### Multiple `input!` calls

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates using the `input!` macro multiple times to read subsequent input, even if the previous read stopped mid-line.

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
# let mut source = AutoSource::from("4 2 1 2 2 3 4 2 1 2 2 3 4");

input! {
#   from &mut source,
    n: usize,
}

for i in 0..n {
    input! {
#       from &mut source,
        m: usize,
        a: [i32; m],
    }
#   assert_eq!(a[0], if i % 2 == 0 { 1 } else { 3 });
#   assert_eq!(a[1], if i % 2 == 0 { 2 } else { 4 });
}

```

--------------------------------

### Reading Arrays and Matrices

Source: https://docs.rs/proconio/%5E0.4.0

Illustrates reading a 2D array (matrix) with specified dimensions.

```rust
use proconio::input;

input! {
    n: usize,
    m: usize,
    a: [[i32; n]; m] // `a` is Vec<Vec<i32>>, (m, n)-matrix.
}
```

--------------------------------

### Reading Tuples

Source: https://docs.rs/proconio/%5E0.4.0

Demonstrates reading a tuple of integers.

```rust
use proconio::input;

input! {
    t: (i32, i32, i32, i32, i32),
}

// if you enter "1 2 3 4 5" to the stdin, `t` is like this.
assert_eq!(t, (1, 2, 3, 4, 5));
```

--------------------------------

### Using `Usize1` and `Isize1` for 0-indexed conversion

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Shows how `Usize1` and `Isize1` markers automatically convert 1-indexed input values to 0-indexed array indices.

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
use proconio::marker::Usize1;
# let mut source = AutoSource::from("4   1 3   3 4   6 1   5 3");

input! {
#   from &mut source,
    n: usize,
    edges: [(Usize1, Usize1); n],
}

// if you enter "4   1 3   3 4   6 1   5 3", the decremented value is stored.
assert_eq!(edges[0], (0, 2));
assert_eq!(edges[1], (2, 3));
assert_eq!(edges[2], (5, 0));
assert_eq!(edges[3], (4, 2));

```

--------------------------------

### input! macro test case: empty input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Test case for the input! macro with empty input.

```Rust
#[test]
fn input_empty() {
let source = AutoSource::from("");
input! {
from source,
}
}
```

--------------------------------

### Runtime Readable Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Demonstrates implementing `RuntimeReadable` for a custom `VecReadable` struct to read a dynamic number of elements into a `Vec`.

```rust
struct VecReadable<T> {
            n: usize,
            _marker: PhantomData<T>,
        }

        impl<T> VecReadable<T> {
            pub fn new(n: usize) -> Self {
                VecReadable {
                    n,
                    _marker: PhantomData,
                }
            }
        }

        impl<T: crate::source::Readable> crate::source::RuntimeReadable for VecReadable<T> {
            type Output = Vec<T::Output>;

            fn read<R: std::io::BufRead, S: crate::source::Source<R>>(
                self,
                source: &mut S,
            ) -> Self::Output {
                let mut res = vec![];
                for _ in 0..self.n {
                    input! {
                        from &mut *source,
                        v: T,
                    }
                    res.push(v);
                }
                res
            }
        }

        let mut source = AutoSource::from("4 1 2 3 4");
        input! {
            from &mut source,
            n: usize,
            v: with VecReadable::<crate::marker::Usize1>::new(n),
        }

        assert_eq!(v, [0, 1, 2, 3]);
```

--------------------------------

### input! macro test case: number input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Test case for the input! macro with various number types.

```Rust
#[test]
fn input_number() {
let source = AutoSource::from("    32   54 -23\r\r\n\nfalse");

input! {
from source,
n: u8,
m: u32,
l: i32,
}

assert_eq!(n, 32);
assert_eq!(m, 54);
assert_eq!(l, -23);
}
```

--------------------------------

### Reading Jagged Arrays

Source: https://docs.rs/proconio/%5E0.4.0

Demonstrates reading a jagged array where inner array sizes can differ, by omitting the inner length.

```rust
use proconio::input;

input! {
    n: usize,
    a: [[i32]; n],
}

// if you enter "3  3 1 2 3  0  2 1 2" to the stdin, the result is as follows.
assert_eq!(
    a,
    vec![
        vec![1, 2, 3],
        vec![],
        vec![1, 2],
    ]
);
```

--------------------------------

### next_token_unwrap method

Source: https://docs.rs/proconio/latest/proconio/source/line/struct.LineSource.html

Method to force retrieval of the next whitespace-splitted token, panicking if none is available.

```rust
fn next_token_unwrap(&mut self) -> &str
```

--------------------------------

### Array or Matrix Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

You can read an array or a matrix like this:

```rust
# extern crate proconio;
# use proconio::source::auto::AutoSource;
use proconio::input;
# let source = AutoSource::from("5 4 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5");

input! {
#    from source,
    n: usize,
    m: usize,
    a: [[i32; n]; m] // `a` is Vec<Vec<i32>>, (m, n)-matrix.
}
# assert_eq!(
#     a,
#     [
#         [1, 2, 3, 4, 5],
#         [1, 2, 3, 4, 5],
#         [1, 2, 3, 4, 5],
#         [1, 2, 3, 4, 5]
#     ]
# );

```

--------------------------------

### Macro definition for input!

Source: https://docs.rs/proconio/latest/proconio/macro.input.html

The complete definition of the proconio input macro.

```rust
macro_rules! input {
    (@from [$source:expr] @rest) => { ... };
    (@from [$source:expr] @rest mut $($rest:tt)*) => { ... };
    (@from [$source:expr] @rest $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @rest $var:tt: $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [] @rest with $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [$($kind:tt)*] @rest) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [$($kind:tt)*] @rest, $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [] @rest [$($tt:tt)*] $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [] @rest ($($tt:tt)*) $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [] @rest $ty:ty, $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @kind [] @rest $ty:ty) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @dyn_kind [$($dyn_kind:tt)*] @rest) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @dyn_kind [$($dyn_kind:tt)*] @rest, $($rest:tt)*) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @dyn_kind [$($dyn_kind:tt)*] @rest $dyn_readable:expr) => { ... };
    (@from [$source:expr] @mut [$($mut:tt)?] @var $var:tt @dyn_kind [$($dyn_kind:tt)*] @rest $dyn_readable:expr, $($rest:tt)*) => { ... };
    (@from $($tt:tt)*) => { ... };
    (from $source:expr, $($rest:tt)*) => { ... };
    ($($rest:tt)*) => { ... };
}
```

--------------------------------

### Single TT Pattern Input

Source: https://docs.rs/proconio/latest/src/proconio/lib.rs.html

Shows how to use a single "tt" pattern for input, destructuring a tuple and reading a fixed-size array.

```rust
fn input_single_tt_pattern() {
        let mut source = AutoSource::from("3 42 0\n1 2 3\n");
        input! {
            from &mut source,
            (n, mut k): (usize, usize),
            _: usize,
            xs: [u32; n],
        }
        k += 1;
        assert_eq!(n, 3);
        assert_eq!(k, 43);
        assert_eq!(xs, [1, 2, 3]);
    }
```

--------------------------------

### LineSource Constructor

Source: https://docs.rs/proconio/latest/proconio/source/line/struct.LineSource.html

Function to create a new LineSource instance from any type implementing BufRead.

```rust
pub fn new(reader: R) -> LineSource<R>
```
Tokens:
Raw