Modify some of the existing examples

Author: qryxip

examples/practice-b-naive.rs

@@ -1,26 +1,35 @@
 // https://atcoder.jp/contests/practice/tasks/practice_2
+//
+// 以下のクレートを使用。
+//
+// - `itertools`
+// - `maplit`
 
 use maplit::hashset;
-
 use std::{io, str};
 
 fn main() {
-    fn read_line() -> String {
-        let mut input = "".to_owned();
-        io::stdin().read_line(&mut input).unwrap();
-        input
-    }
+    let mut input = "".split_ascii_whitespace();
+    let mut read = || loop {
+        if let Some(word) = input.next() {
+            break word;
+        }
+        input = {
+            let mut input = "".to_owned();
+            io::stdin().read_line(&mut input).unwrap();
+            if input.is_empty() {
+                panic!("reached EOF");
+            }
+            Box::leak(input.into_boxed_str()).split_ascii_whitespace()
+        };
+    };
+    macro_rules! read(($ty:ty) => (read().parse::<$ty>().unwrap()));
 
-    fn query(l: u8, r: u8) -> bool {
-        println!("? {} {}", l as char, r as char);
-        read_line() == "<\n"
-    }
+    let (n, _): (u32, u32) = (read!(u32), read!(u32));
 
-    let n = {
-        let input = read_line();
-        let mut input = input.split_whitespace();
-        macro_rules! read(($ty:ty) => (input.next().unwrap().parse::<$ty>().unwrap()));
-        read!(u32)
+    let query = |l: u8, r: u8| -> bool {
+        println!("? {} {}", l as char, r as char);
+        read!(char) == '<'
     };
 
     let ans = match n {

examples/practice-b-proconio.rs

@@ -1,26 +1,35 @@
 // https://atcoder.jp/contests/practice/tasks/practice_2
+//
+// 以下のクレートを使用。
+//
+// - `itertools`
+// - `maplit`
+// - `proconio`
 
 use maplit::hashset;
-use proconio::input;
-use proconio::source::line::LineSource;
-
-use std::{io, str};
+use proconio::{input, source::line::LineSource};
+use std::{
+    io::{self, BufReader},
+    str,
+};
 
 fn main() {
-    let stdin = io::stdin();
-    let mut stdin = stdin.lock();
+    // `proconio::input!`はrelease modeではデフォルトでは`OnceSource`を使ってしまうので、
+    // `input! { from: .., }`で`LineSource`を指定する必要がある。
+    // `Source`を指定するときはこのように部分適用したマクロを用意しておくと楽。
+    //
+    // https://docs.rs/proconio/0.3.6/proconio/macro.input.html
+    // https://docs.rs/proconio/0.3.6/proconio/source/once/struct.OnceSource.html
+    // https://docs.rs/proconio/0.3.6/proconio/source/line/struct.LineSource.html
+    // https://docs.rs/proconio/0.3.6/proconio/source/trait.Source.html
+    let mut stdin = LineSource::new(BufReader::new(io::stdin()));
+    macro_rules! input(($($tt:tt)*) => (proconio::input!(from &mut stdin, $($tt)*)));
 
-    input! {
-        from LineSource::new(&mut stdin),
-        n: u32,
-    }
+    input!(n: u32, _: u32);
 
     let query = |l: u8, r: u8| -> _ {
         println!("? {} {}", l as char, r as char);
-        input! {
-            from LineSource::new(&mut stdin),
-            c: char,
-        }
+        input!(c: char);
         c == '<'
     };
 

examples/practice-b-text-io.rs

@@ -1,25 +1,22 @@
 // https://atcoder.jp/contests/practice/tasks/practice_2
+//
+// 以下のクレートを使用。
+//
+// - `itertools`
+// - `maplit`
+// - `text_io`
 
 use maplit::hashset;
+use std::str;
 use text_io::read;
 
-use std::{io, str};
-
 fn main() {
-    fn read_line() -> String {
-        let mut input = "".to_owned();
-        io::stdin().read_line(&mut input).unwrap();
-        input
-    }
-
-    let n: u32 = {
-        let line = read_line();
-        read!("{}", line.bytes())
-    };
+    let (n, _): (u32, u32) = (read!(), read!());
 
     let query = |l: u8, r: u8| -> _ {
         println!("? {} {}", l as char, r as char);
-        read_line() == "<\n"
+        let c: char = read!();
+        c == '<'
     };
 
     let ans = match n {

examples/practice-b-whiteread.rs

@@ -1,9 +1,14 @@
 // https://atcoder.jp/contests/practice/tasks/practice_2
+//
+// 以下のクレートを使用。
+//
+// - `itertools`
+// - `maplit`
+// - `whiteread`
 
 use maplit::hashset;
-use whiteread::Reader;
-
 use std::str;
+use whiteread::Reader;
 
 fn main() {
     let mut rdr = Reader::from_stdin_naive();