Add an example for panasonic2020_d

qryxip · qryxip · commit 614eae595deb · 2020-05-19T00:20:09.000+09:00
diff --git a/examples/panasonic2020-d.rs b/examples/panasonic2020-d.rs
@@ -0,0 +1,46 @@
+// https://atcoder.jp/contests/panasonic2020/tasks/panasonic2020_d
+//
+// 以下のクレートを使用。
+//
+// - `proconio`
+// - `smallvec`
+
+use proconio::{fastout, input};
+use smallvec::{smallvec, Array, SmallVec};
+
+use std::collections::VecDeque;
+use std::{cmp, str};
+
+// `#[proconio::fastout]`で標準出力を高速化する。
+//
+// https://docs.rs/proconio-derive/0.1.6/proconio_derive/attr.fastout.html
+#[fastout]
+fn main() {
+    // `proconio::input!`。
+    //
+    // https://docs.rs/proconio/0.3.6/proconio/macro.input.html
+    input! {
+        n: usize,
+    }
+
+    // **高々**長さ10の文字列を`SmallVec<[u8; 10]>`で表わす。
+    //
+    // https://docs.rs/smallvec/1/smallvec/struct.SmallVec.html
+    let mut queue = VecDeque::<(SmallVec<[_; 10]>, _)>::with_capacity(1 << 16);
+    queue.push_back((smallvec![b'a'], b'a'));
+
+    while let Some((s, max)) = queue.pop_front() {
+        if s.len() == n {
+            println!("{}", str::from_utf8(&s).unwrap());
+        } else {
+            for c in b'a'..=max + 1 {
+                queue.push_back((concat(s.clone(), c), cmp::max(c, max)));
+            }
+        }
+    }
+}
+
+fn concat<A: Array>(mut xs: SmallVec<A>, x: A::Item) -> SmallVec<A> {
+    xs.push(x);
+    xs
+}
diff --git a/test-examples.toml b/test-examples.toml
@@ -241,6 +241,13 @@ url = "https://atcoder.jp/contests/atc002/tasks/atc002_b"
 matching = "Words"
 meta = { using = ["num", "proconio"] }
 
+[examples.panasonic2020-d]
+type = "Normal"
+name = "Panasonic Programming Contest 2020: D - String Equivalence"
+url = "https://atcoder.jp/contests/panasonic2020/tasks/panasonic2020_d"
+matching = "Words"
+meta = { using = ["proconio", "smallvec"] }
+
 [examples.practice-a-naive]
 type = "Normal"
 name = "practice contest: A - Welcome to AtCoder"
