From 5921b577c0bad37b17d6b068e034d38cad5f578a Mon Sep 17 00:00:00 2001
From: YK <yk@qcl.one>
Date: Mon, 2 Dec 2024 08:44:42 +0300
Subject: [PATCH] solution: day 2 + add BinaryHeap re-export

---
 src/days.rs    |  2 +-
 src/days/d2.rs | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++
 src/prelude.rs |  7 ++++-
 3 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 src/days/d2.rs

diff --git a/src/days.rs b/src/days.rs
index e88513f..c31753b 100644
--- a/src/days.rs
+++ b/src/days.rs
@@ -1,5 +1,5 @@
 pub mod d1;
-// pub mod d2;
+pub mod d2;
 // pub mod d3;
 // pub mod d4;
 // pub mod d5;
diff --git a/src/days/d2.rs b/src/days/d2.rs
new file mode 100644
index 0000000..a83ecde
--- /dev/null
+++ b/src/days/d2.rs
@@ -0,0 +1,70 @@
+use crate::prelude::*;
+
+pub type I = Vec<Vec<i32>>;
+pub type O = usize;
+
+fn _parse (data: &str) -> I {
+    data.lines().map(|line| line.split_ascii_whitespace().map(|e| p!(e)).collect()).collect()
+}
+
+fn _report_safety (report: &[i32]) -> bool {
+    let dir = report[0] - report[1];
+    if dir.abs() < 1 || dir.abs() > 3 { return false; }
+    for &[a, b] in (&report[1..]).array_windows() {
+        let diff = a - b;
+        let abs = diff.abs();
+        if diff.signum() != dir.signum() { return false; }
+        if abs < 1 || abs > 3 { return false }
+    }
+
+    true
+}
+
+fn _silver (data: &I) -> O {
+    data.into_iter().filter(|s| _report_safety(s)).count()
+}
+
+fn _gold (data: &I) -> O {
+    data.into_iter().filter(|report| {
+        let mut s = vec![report.to_vec()];
+        for i in 0..report.len() {
+            s.push([&report[..i], &report[i+1..]].concat());
+        }
+        s.iter().any(|report| _report_safety(report))
+
+    }).count()
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    fn read () -> I {
+        let data = inc!(2);
+        _parse(data)
+    }
+
+    #[test]
+    fn sample () {
+        let data = inc!("2_example");
+        let data = _parse(data);
+
+        assert_eq!(_gold(&data), 4)
+    }
+
+    #[test]
+    fn silver () {
+        let data = read();
+        let ans = _silver(&data);
+
+        assert_eq!(ans, 510)
+    }
+
+    #[test]
+    fn gold () {
+        let data = read();
+        let ans = _gold(&data);
+
+        assert_eq!(ans, 553)
+    }
+}
diff --git a/src/prelude.rs b/src/prelude.rs
index b91437e..3305376 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -2,7 +2,12 @@ pub use crate::utils::*;
 pub use anyhow::Error;
 pub use itertools::Itertools;
 pub use std::{
-    collections::{ HashMap as M, HashSet as S, VecDeque as D },
+    collections::{
+        HashMap as M,
+        HashSet as S,
+        VecDeque as D,
+        BinaryHeap as B,
+    },
     cmp::Ordering as Or,
 };